Patent ID: 8858898

Claim:
A pipette tip member for releasably mating with a pipette shaft and transferring liquid, having an elongated tubular receptacle which comprises: a proximal opening for receiving a pipette shaft; a distal tip opening for dispending liquid from said pipette tip member; and an upper wall section adjacent said proximal opening for removably engaging said pipette shaft and having coaxially a sealing layer and a supporting layer, said upper wall section comprising an external shoulder near the distal end of said upper wall section sufficient to prevent excess downward sliding movement of said pipette shaft toward said distal tip opening, wherein said supporting layer has a greater hardness (as measured according to ASTM test D 2240) than the sealing layer, and wherein said sealing layer is on an outer peripheral surface of said upper wall section and around an entire circumference, and said sealing layer is of a length extending from said proximal opening to said shoulder, and wherein when said pipette tip member is mounted onto said pipette shaft said sealing layer is in sealing contact with an inner surface of said pipette shaft.