Patent Description:
While the prior art seal performs in a satisfactory manner, and is comfortable to a user, leakage can be experienced, particularly in certain areas which are known to be difficult to seal. Such areas include, for example, areas around the nose and the bridge of the nose.

Disclosed are instances of a sealing element for sealing an air gap between the face of a user and a facemask, the sealing element comprised of a formed flexible material having a durometer value of <NUM> or less on a Type <NUM> scale, the sealing element having at least three primary external faces comprising: a) a facemask attachment face; b) a skin contact face; and c) a third face wherein, when viewed in cross-section, the skin contact face is the longest of the three faces. Also disclosed are instances of the sealing element of as described above wherein the formed flexible material comprises a sealed, flexible external membrane bladder containing a fluid or a gel. Disclosed are instances of the sealing element described above wherein the external membrane bladder is formed from a thermopolymer and the gel is a silicone gel. Disclosed are instances of the sealing element described above wherein the external membrane bladder is formed by bonding a first and a second thermopolymer sheet portion. Also disclosed are instances of the sealing element described above wherein the first thermopolymer sheet portion is drawn under heat and vacuum to form the skin contact face and the third face. Disclosed are instances of the sealing element described above wherein, when viewed in cross section, the side corresponding to the third face has a length which is less than about <NUM>% - <NUM>% of the length of the skin contact face. Further disclosed are instances of the sealing element described above further comprising one or more local lobe domains having an extended skin contact face and an extended third face, as compared with adjacent non-lobe portions, for the purpose of sealing areas of substantial variation in the facial structure of the user. Disclosed are instances wherein the one or more local lobe domains comprise an upper portion and a lower portion, wherein the lower portion is generally rectangular in shape, the height of the rectangle approximating the height of adjacent, non-lobe portions of the sealing element; and the upper portion is generally trapezoidal in shape, wherein the angled sides of the trapezoid form an average angle of between <NUM> degrees and <NUM> degrees with the top of the rectangular lower portion. Further disclosed are instances of the sealing element described above wherein the angle formed between the attachment face and the third face is between <NUM> degrees and <NUM> degrees.

Further disclosed are instances of a facemask comprising: a) a housing defining a facemask chamber, the housing comprising a continuous attachment flange; and b) a sealing element adhesively attached to the attachment flange and configured to form a seal between the attachment flange of the housing and the face of a user, the sealing element comprised of a formed flexible material having a durometer value of <NUM> or less on a Type <NUM> scale, the sealing element having at least three primary external faces comprising: i) a facemask attachment face; ii) a skin contact face; and iii) a third face, wherein, when viewed in cross-section, the skin contact face is the longest of the three faces. Also disclosed are instances of the facemask wherein the attachment flange slopes inwardly along at least a majority of its surface length. Further disclosed are instances of the facemask described above wherein the formed flexible material comprises a sealed, flexible external membrane bladder containing a fluid or a gel. Also disclosed are instances of the facemask as described above wherein the external membrane bladder is formed from a thermopolymer and the gel is a silicone gel. Disclosed are instances of the facemask described above wherein the external membrane bladder is formed by bonding a first and a second thermopolymer sheet portion. Disclosed are instances of the facemask described, wherein the first thermopolymer sheet portion is drawn under heat and vacuum to form the skin contact face and the third face. Further disclosed are instances of the facemask described wherein, when the bladder is viewed in cross section, the side corresponding to the third face has a length which is less than about <NUM>% - <NUM>% of the length of the skin contact face. Described are instances of the facemask described above further comprising one or more local lobe domains having an extended skin contact face and an extended third face, relative to adjacent non-lobe domains, for the purpose of sealing areas of substantial variation in the facial structure of the user. Disclosed are instances of the facemask described above wherein the majority of the surface of the attachment flange slopes inwardly at least <NUM> degrees. Also disclosed are instances of the facemask described above wherein the majority of the surface of the attachment flange slopes inwardly from about <NUM> degree to about <NUM> degrees. Disclosed are instances of the facemask described above wherein the surface area of the seal formed between the skin contact face of the sealing element and the face of the user is greater than the surface area formed by an otherwise identical facemask having a semi-circular sealing element of substantially identical height. Also disclosed are instances of the facemask described above wherein the surface area of the seal formed between the skin contact face of the sealing element and the face of the user is greater than the surface area formed by an otherwise identical facemask having a semi-circular sealing element of substantially identical volume. Disclosed are instances of the facemask described above wherein the angle formed between the attachment face and the third face is between <NUM> degrees and <NUM> degrees. <CIT> describes a respiratory mask with an improved flexible respiratory mask face seal.

The present disclosure is directed toward a new and non-obvious improvement in a sealing element for sealing the air gap between the face of a user and a facemask. The present disclosure is also related to a facemask comprising the sealing element of the present disclosure. In the context of the present disclosure a "facemask" is defined as a mask sized to fit over a user's nose (nasal mask), a mask sized to fit over a user's nose and mouth (but not eyes and chin), a mask sized to fit over a user's nose, mouth and eyes (but not chin) and a mask sized to fit over a user's nose, mouth, eyes and chin. In a preferred instance, the facemask is a mask that fits over a user's nose and mouth. Any type of facemask falls within the scope of the present disclosure. Exemplified is a dust mask with support ribs for supporting a replaceable filter element (not shown). The full scope of the disclosure extends to any mask worn over the face for the purpose of sealing out the external environment. This includes, for example, all forms of respiratory masks including continuous positive airway pressure (CPAP) masks.

As mentioned above, while the prior art seal performs in a satisfactory manner, and is comfortable to a user, leakage can be experienced, particularly in certain areas which are known to be difficult to seal. Such areas include, for example, areas around the nose and the bridge of the nose. The facemask seal of the present disclosure has been shown to perform in a superior manner, while having otherwise similar characteristics (e.g., comfort, cost, weight, shelf life, etc.).

The sealing element of the present disclosure can be comprised of one or more formed flexible materials having a durometer value of <NUM> or less on a Type <NUM> Shore scale; a durometer value of <NUM> or less on a Type <NUM> Shore scale; a durometer value of <NUM> or less on a Type <NUM> Shore scale; a durometer value of <NUM> or less on a Type <NUM> Shore scale; a durometer value of <NUM> or less on a Type <NUM> Shore scale or a durometer value of <NUM> or less on a Type <NUM> Shore scale. Exemplary formed flexible materials suitable for use in the sealing element of the present disclosure are, for example, silicone gel bladder, air filled bladder, foam (of various types known to one of ordinary skill in the art) and rubber (natural or synthetic).

The Shore durometer is a device known to one of ordinary skill in the art for measuring the hardness of a material, typically of polymers, elastomers, and rubbers. Higher numbers on the scale indicate a greater resistance to indentation and thus harder materials. Lower numbers indicate less resistance and softer materials. The term is also used to describe a material's rating on the scale, as in an object having a "'Shore durometer of <NUM>. " Shore durometers are designed to measure specific scale ranges. A Type <NUM> durometer measures the hardness of very soft materials.

Instances of the sealing element <NUM> of the present disclosure comprises at least three primary external faces as shown in <FIG>. Describing instances of the disclosure in cross-section, the skin contact face <NUM> is always the longest face. The attachment face <NUM> can be longer than, shorter than or equal in length to the third face <NUM>. In preferred instances, the third face <NUM> has a length which is less than about <NUM>% to <NUM>% of the length of the skin contact face <NUM>. In instances of the triangular seal of the present disclosure, the angle formed between the attachment face <NUM> and the third face <NUM> is between <NUM> degrees and <NUM> degrees. As will be discussed below, for manufacturing reasons, a range of between <NUM> degrees and <NUM> degrees is preferred.

Further still, the third face <NUM> occupies the inner perimeter of the sealing element and the skin contact face <NUM> occupies the outer perimeter of the sealing element, as shown in <FIG>. In cross-section, the transition between the faces of the triangle of the sealing element of the present disclosure, particularly the transition (<NUM> in <FIG> and <NUM> in <FIG>) between the third face and the skin contact face, appear rounded, slightly rounded or even flat. The reason for the rounded or even flat nature of this transition will become clear following consideration of a preferred manufacturing process described below.

In other instances, the sealing element of the present disclosure can have more than <NUM> primary faces. One skilled in the art will recognize, for example, that a trapezoidal seal will offer many of the advantages described herein in connection with a triangular instance, and one skilled in the art, guided by the present disclosure, can make and use such trapezoidal seals using no more than routine experimentation.

In comparison, a prior art sealing element, as shown in <FIG>, has the shape of a modified semi-circle. A modified semi-circle, as defined herein, is a half or semi-circle shape <NUM> extending from a rectangular base <NUM>. The prior art sealing element also has an attachment face <NUM> for attachment to a mask.

In one instance of the present disclosure, the formed flexible material of the sealing element comprises an external membrane bladder (<FIG>, <NUM> & <NUM> and <FIG>, <NUM> & <NUM>) containing a fluid or gel (<FIG>, <NUM> and <FIG>, <NUM>). In an instance of the present disclosure, the external membrane bladder is formed from one or more thermopolymer sheets (for example, <NUM> and <NUM> in <FIG>). Thermopolymer sheet material is known to one of ordinary skill in the art. Examples of such materials include sheets comprising urethane, polyurethane, latex, nitrile and other natural polymers and synthetic polymers. The bladder may be formed from a sheet of thermopolymer comprising, for example, a first and a second thermopolymer sheet portion. The term "thermopolymer sheet portion" is defined to mean a portion of a single sheet folded or otherwise manipulated to form more than one face of the three faces of the sealing element of the present disclosure. Thus, a sheet of thermopolymer material may comprise one or more thermopolymer sheet portions. As can be seen in <FIG>, for example, attachment face <NUM> is bounded by a thermopolymer sheet and skin contact face <NUM> and third face <NUM> are bounded by a second thermopolymer sheet.

In one instance, the bladder is formed by drawing a first thermopolymer sheet portion into a molding apparatus with heat and vacuum to form the skin contact face and the third face of the sealing element of the present disclosure. A molding apparatus is, in its simplest form, a vacuum mold having a cavity or well in the shape of the skin contact face and third face of the sealing element of the present disclosure. Again, referring to <FIG> for example, in a first step, a polymer sheet is heated and drawn under vacuum to form the exterior bladder boundary of the skin contact face <NUM> and the third face <NUM>. The vacuum is created through the use of air holes in the bottom of the mold cavity. Because the skin contact face <NUM> and the third face <NUM> meet at the bottom of the heated vacuum cavity, the transition between those faces tends to be rounded, thereby enabling removal of the molded product and generally facilitating the process. In instances, a gel is then poured into the mold to fill the cavity formed by the first polymer sheet. A second polymer sheet (or another portion of the same polymer sheet) is overlaid on the gel-filled cavity and the edges of the two polymer sheets are heat-bonded to seal the gel within a continuous thermopolymer sheet bladder.

When drawn under heat and vacuum, the drawn thermopolymer sheet portion(s) will be made thinner than the starting stock material. One of skill in the art will recognize the effects of vacuum drawing on thermopolymer sheet thickness. For particular applications, one of skill in the art may select polymer sheets having varying thicknesses. For example, a thinner film will maximize the ability for the filled bladder to contour. Thicker films must be used for deeper draws in the heated mold.

In instances having one or more local lobes <NUM>, as, for example, in <FIG> and <FIG>, the cavity of the molding apparatus contains a local cavity (i.e., a cavity deeper than the cavity forming adjacent non-lobe portions) deepening the draw to form the one or more local lobes <NUM>. As discussed in connection with <FIG>, local lobe(s) have an upper portion and a lower portion. The upper and lower portion of local lobe(s) <NUM> may be alternatively referred to herein as local lobe domains <NUM>. The upper portion of local lobes <NUM> are both local and prominent, rising dramatically from the non-lobe portions of the sealing element <NUM>. As indicated elsewhere, the location of the local lobes corresponds with areas of dramatic feature change in the contour of a face to be fit (e.g., around the nose and the bridge of the nose).

<FIG> is a top projection view of a sealing element <NUM> of the present disclosure. The seal of the present disclosure can be viewed as comprising <NUM> segments: A, B and C. Segments A and B are designed to seal an area of the face extending from the nose and the bridge of the nose at the intersection of segments A and B, and extending down to the sides of the mouth defined by the two termini of segment C.

<FIG> shows a side projection view along segment A of <FIG>, including a local lobe domain <NUM>. As can be seen, the upper portion of the local lobe rises dramatically from the adjacent non-lobe portions of the sealing element <NUM>. The upper portion of the local lobes <NUM> rising from the adjacent non-lobe portions of the sealing element <NUM> tend to be trapezoidal in shape based on the manufacturing process (discussed elsewhere herein). As shown in <FIG>, the side projection of the local lobe <NUM> can be broken down into a generally rectangular (or lower) portion <NUM> the height of which approximates the height of side projections of adjacent non-lobe portions of the sealing element <NUM>, and a generally trapezoidal portion <NUM> sitting atop the rectangular portion <NUM>. The trapezoidal portion <NUM> represents the local lobe <NUM> rising dramatically from the adjacent non-lobe portions of the sealing element <NUM>. The angled side legs of the trapezoid form an average angle <NUM> and <NUM> with the top of the rectangular portion <NUM> and the average angle <NUM> and <NUM> is preferably between <NUM> degrees and <NUM> degrees. One of skill in the art will recognize that average angles <NUM> and <NUM> can differ dramatically from one another, but will fall within the preferred range of <NUM> degrees to <NUM> degrees.

In designing the local lobes, one of skill in the art will recognize and consider several important design factors. The lobe must be large enough to seal around features of the face with dramatic structural changes. An example given previously is the nose and the bridge of the nose. It will also be recognized that lobes that are too large will also result in a "leaky" seal caused by the upper portion of the local lobe <NUM> lifting the adjacent non-lobe portion off the face.

As discussed elsewhere, and depicted diagrammatically in <FIG>, certain instances of prior art sealing elements can be described as "U-shaped" or "modified or extended semi-circular shaped". <FIG> shows a top projection view of such a prior art seal. This prior art seal can be viewed as comprising <NUM> segments: A, B and C. Some instances of such prior art seals have been designed to include one or more mildly sloping raised portions as shown, for example in <FIG>, which represent a side projection of segment A from <FIG>. This mildly sloping raised portion can be viewed as a portion of a segment <NUM> with an arc <NUM> whose cord length <NUM> is <NUM>% or more of the segment length <NUM> (segment A) and the peak of the arc extends <NUM> - <NUM>% of the base height <NUM> of the prior art seal.

Silicone gel is the preferred material for filling the thermopolymer bladder of the sealing element of the present disclosure. The silicone gel material of the present disclosure, when formed into the sealing element of the present disclosure, has a durometer value of <NUM> or less on a Type <NUM> Shore scale; a durometer value of <NUM> or less on a Type <NUM> Shore scale; a durometer value of <NUM> or less on a Type <NUM> Shore scale; a durometer value of <NUM> or less on a Type <NUM> Shore scale; a durometer value of <NUM> or less on a Type <NUM> Shore scale or a durometer value of <NUM> or less on a Type <NUM> Shore scale.

Other materials, as discussed above, are also suitable for the use as the sealing element of the present disclosure. Other materials may or may not require a bladder. For example, foam or rubber may be molded or otherwise shaped (e.g., by cutting) without the need for a bladder.

As shown in <FIG> and <FIG>, the sealing element of the present disclosure may further comprise one or more local lobes <NUM> extending the skin contact face <NUM> and the third face <NUM> for sealing areas of substantial variation in facial structure of the user. For example, on a mask that covers the nose and mouth, but not the eyes, local lobes <NUM> may be located at the portion of the sealing element that positions on either side of the nose and the bridge of the nose to compensate for the extreme change in contour of the face at this position. As mentioned elsewhere, the expressions "local lobe" and "local lobe domain", singular or plural, may be used interchangeably herein. Likewise, local lobes may be advantageous on sealing elements used on nasal and facemasks covering the eyes, as well as the nose and mouth, as areas of substantial variation in facial structure can vary depending on the type of mask used. For example, nasal masks may require local lobes on either side of the nose and the bridge of the nose and facemasks covering the eyes may require local lobes adjacent to the eye sockets, under the lower lip or at the cheeks. As shown in <FIG>, the local lobe domain <NUM> comprises a skin contact face <NUM>, an attachment face <NUM> and a third face <NUM>. As discussed elsewhere, the area of transition <NUM> between the skin contact face <NUM> and the third face <NUM> tends to resemble a rounded transition, or even a flat spot, due to manufacturing techniques. In essence, the local lobe extends the third face <NUM> and the skin contact face <NUM> proportionally thereby maintaining the profile of the adjacent non-lobe regions.

In another instance, the present disclosure relates to a facemask (e.g., nasal or other facemask, as described above) comprising a sealing element of the present disclosure, as described above and exemplified herein. As shown in <FIG> and <FIG>, the facemask may have, for example, a housing that defines a chamber <NUM>, the housing comprising a continuous facemask attachment flange <NUM>, the continuous facemask attachment flange being located, for example, at the periphery of the chamber. The facemask attachment flange is also shown in cross-section in <FIG>. The sealing element <NUM> of the present disclosure is attached to the facemask attachment flange <NUM> via the attachment face (e.g., <NUM> and <NUM>) of the sealing element thereby being configured to form a seal between the attachment flange of the facemask housing and the face of a user. The sealing element of the present disclosure may be attached to the attachment flange with any method known to one of ordinary skill in the art such as, for example, adhesive and/or heat. The attachment flange <NUM> is perhaps shown best in the exploded perspective of <FIG>. In <FIG>, the sealing element <NUM> is depicted as detached from the attachment flange <NUM>.

As shown in <FIG>, a portion of the attachment flange <NUM> of the facemask is angled to slope inwardly along at least a majority of its surface length. The inwardly sloping attachment flange aids in the positioning of the sealing element of the present disclosure to ensure that the skin contact face <NUM> of the sealing element makes maximum contact with the user's face. The superior contact and seal provided by the sealing element of the present disclosure versus the prior art sealing element are shown diagrammatically in <FIG> (prior art seal) and <NUM> (sealing element of the present disclosure). The materials and methods utilized to generate the data depicted diagrammatically in <FIG> is set forth in the Exemplification section which follows.

The portion (percent) of the length of the attachment flange that slopes inwardly depends on the type of mask used (e.g., nasal or facemask type as discussed above). In any event, the percent of the attachment flange that slopes inwardly is at least <NUM> %; at least <NUM> %; at least <NUM> % or at least <NUM> % of its surface length. The attachment flange slopes inwardly at least <NUM> degrees; at least <NUM> degrees; at least <NUM> degrees; at least <NUM> degrees; at least <NUM> degrees or at least <NUM> degrees. The attachment flange slopes inwardly from about <NUM> degrees to about <NUM> degrees, from about <NUM> degrees to about <NUM> degrees or about <NUM> degrees to about <NUM> degrees. In one aspect, for example, for a facemask covering only the nose and mouth, the sides of the mask (i.e., the portions relative to the seal that contact a user's cheeks) angle inwardly to a greater extent than at the top and bottom of the mask (i.e., the portions relative to the seal that contact a user's nose bridge and chin, respectively). A non-angled portion of an attachment flange is shown in cross-section in <FIG>. This portion of the attachment flange <NUM> is position above the bridge of the nose, for example.

The sealing element of the facemask of the present disclosure comprises at least three primary external face as, as described above. The sealing element of the facemask of the present disclosure forms a seal between the skin contact face of the sealing element of the facemask and the face of the user when worn by the user. The surface area of the seal formed between the skin contact face of the sealing element of the present disclosure and the face of the user is greater than the surface area formed by an otherwise identical facemask having a semi-circular or modified semi-circular (described in the Exemplification section, below) sealing element of substantially identical height (but less volume). Further, the surface area of the seal formed between the skin contact face of the sealing element of the present disclosure and the face of the user is greater than the surface area formed by an otherwise identical facemask having a semi-circular or modified semi-circular (described in the Exemplification section, below) sealing element of substantially identical volume (but greater height).

The sealing element of the facemask of the present disclosure can be comprised of one or more formed flexible materials having a durometer value of <NUM> or less on a Type <NUM> Shore scale; a durometer value of <NUM> or less on a Type <NUM> Shore scale; a durometer value of <NUM> or less on a Type <NUM> Shore scale; a durometer value of <NUM> or less on a Type <NUM> Shore scale; a durometer value of <NUM> or less on a Type <NUM> Shore scale or a durometer value of <NUM> or less on a Type <NUM> Shore scale. Exemplary formed flexible materials suitable for use in the sealing element of the present disclosure are, for example, silicone gel, foam (of various types known to one of ordinary skill in the art) and rubber (natural or synthetic).

The seal formed between a user's face and a triangular instance of the sealing element of the present disclosure was studied and characterized. The seal, studied and characterized in this manner, was compared with a seal formed between a user's face and a prior art semi-circular seal having a volume approximating that of the triangular instance of the sealing element of the present disclosure. The footprint density of the seal formed by the triangular instance of the sealing element of the present disclosure was estimated to be <NUM>% - <NUM>% greater than the footprint density of the semi-circular seal having a volume approximating that of the triangular instance of the sealing element of the present disclosure.

The seal formed between a user's face and an instance of the sealing element of the present disclosure was studied using a male display head in white from Zing Display (<NUM> Oso Parkway D136, Rancho Santa Margarita, CA). A facemask frame, including an attachment flange as described herein, was fitted with an instance of the sealing element of the present disclosure. A cross-section of the sealing element of the present disclosure was triangular in configuration. More specifically, it was a triangular configuration with the third face having a length of <NUM> inches, a skin contact face having a length of <NUM> inches and an attachment face having a length of <NUM> inches. The height of the sealing element was <NUM> inches. The volume of the sealing element of the present disclosure was <NUM>.

The seal formed between a user's face and a prior art modified semi-circular sealing element of was studied using an identical male display head in white from Zing Display. A facemask frame, as described in the previous paragraph, was fitted with the prior art sealing element. The height of the modified semicircular sealing element was <NUM> inches. The volume of the prior art sealing element was <NUM>. As indicated, an effort was made to compare sealing elements of substantially identical volume and height, but due to molding considerations, some differential was necessary. Specifically, the sealing element of the present disclosure had a volume approximately <NUM>% greater, and a height approximately <NUM>% greater than the prior art sealing element. This difference was deemed acceptable and is taken into account when interpreting results.

Both the sealing element instance of the present disclosure and the sealing element of the prior art comprise an external membrane made from a first and a second thermopolymer sheet portion containing a silicone gel having a durometer value of approximately <NUM> using <NUM> Shore scale. Both sealing elements were attached to a substantially identical facemask frame having an attachment flange which sloped inwardly at about <NUM> to <NUM> degrees along the mask to contour to a typical face.

The skin contact face of the sealing element of the present disclosure and the semi-circle arc of the prior art sealing element were marked using a black lipstick. Lipstick applied in this manner was demonstrated to transfer, upon contact, with the display head. With regard to the sealing element of the present disclosure, application of the lipstick to the third face was avoided to prevent false readings that may be caused when the third face inadvertently moved while being positioned on the display head. Further, lipstick was not applied to some area of the sealing element to avoid the fingerprint effect of making an impression where only intermittent contact was made during positioning of the mask. Some judgement was used here by observing how the sealing element rested on the manikin after reaching maximum contact.

Following application of the lipstick, the sealing elements were brought into contact with the display heads, mimicking use. Downward force (i.e., in a vector toward the face of the display head) was applied to each facemask frame making each sealing element pivot (i.e., roll towards the center of the mask) to its maximum angle, similar to when worn by a user. The black lipstick was transferred to the display heads leaving a record of the contact surface area for each sealing element. Both sealing elements transferred wax to the display head remarkably well.

The density of wax transfer to display heads using each of the sealing elements was estimated to be <NUM>% - <NUM>% greater for the sealing element of the present disclosure as compared with the prior art sealing element. This visual estimate can be confirmed by photographic densitometry measurements. Graphic representations of the wax transfer observations are shown in <FIG> (prior art sealing element) and <FIG> (sealing element of the present disclosure). Aside from the visual density estimates, it can be seen in <FIG> that the prior art sealing element failed to make contact in areas around the nose and the bridge of the nose. <FIG> shows good contact in trouble areas such as the area around the nose and the bridge of the nose and the corners of the mouth.

The density of the wax transfer and overall quality of the contact observed with the triangular sealing element of the present disclosure was surprising when compared with the prior art modified semi-circular sealing element observations. Although the volume of the triangular sealing element of the present disclosure was approximately <NUM>% greater than the volume of the prior art modified semi-circular sealing element, and the height of the triangular sealing element of the present disclosure was approximately <NUM>% greater than the height of the prior art modified semi-circular sealing element, these differences alone do not account for the dramatic increase in lipstick transfer.

Claim 1:
A facemask sized to fit over a user's nose, a user's nose and mouth, or a user's nose, mouth, and eyes, the facemask comprising:
a) a housing defining a facemask chamber (<NUM>), the housing comprising a continuous attachment flange (<NUM>); and
b) a sealing element (<NUM>) attached to the attachment flange, the sealing element configured to form a seal between the housing and the face of a user, the sealing element comprised of a formed flexible material having a durometer value of <NUM> or less on a Type <NUM> scale and having three primary external faces comprising:
(i) a facemask attachment face (<NUM>);
(ii) a skin contact face (<NUM>) occupying an outer perimeter of the sealing element; and
(iii) a third face (<NUM>) occupying an inner perimeter of the sealing element;
wherein the continuous attachment flange comprises an attachment surface, the facemask attachment face is in contact with the attachment surface and the third face extends from the attachment surface;
wherein, when the sealing element is viewed in cross-section, the skin contact face is the longest of the three primary external faces; and
wherein, when the sealing element is viewed in cross section, the third face has a length which is less than <NUM>% to <NUM>% of a length of the skin contact face,
characterized in that the sealing element is triangular in cross-section, and the transition between the skin contact face and the third face is rounded, slightly rounded or flat.