The mask itself is constructed from neoprene rubber or silicon and is held in place by a five point adjustable harness with each point being adjustable. All sets are required to be positive pressure to prevent an inflow of toxic gases if the facemask is dislodged. Masks have a supplementary air flow button to allow extra air to be pushed onto the face if the need arises. The demand valve is usually activated on a first breath system which switches the sets into positive mode. The cylinder is a 9 litre water capacity or 1800 litre air charged to 207 bar or 3000psi.
Brigades have at present only one cylinder on each set.
The contents is 45 minutes usuing an average of 40 litres a minute. Cylinders are at present changing to carbon composite lightweight throughout the country. A slip on cover made from nomex or plastic is placed over the cylinder to prevent scuffing and general marking of the cylinder. Newly introduced to Dublin Fire Brigade is a cylinder valve handle which is on a spring and has to be pulled out to turn off the cylinder. This was introduced after air had been turned off when a valve rolled closed while coming down a stairwell with the valve wheel rubbing on the railing.