Rodent face masks are made from clear acrylic and fit all non-rebreathing systems. This system is designed for use with the Mapleson-D style nonrebreathing system AS-01-0500-07 The diaphragms on these masks seal the mask around the face of the rodent and reduce the amount of anesthetic gases that may leak into the room. Face mask diaphragms are made from 12 mil thick latex and openings can be cut in the diaphragm to accommodate rodents of different sizes. Comes with extra diaphragm material.