Description BMC masks are compatible with the machines and pipes from other brands. The latest in BMC full face mask range is the F6. This revolutionary design gives a new meaning to a comfortable full face mask providing an open, non-constrictive feel. The under the nose cushion minimises claustrophobia and brings relieve to the nasal bridge. Noise levels are kept as low as  17dB by the circular dispersion vent, your partner will be delighted as the disturbance is minimal. Simple, light weight design. Increased comfort with single layer cushion. A crown-styled adjustable headgear allows for a comfortable fit that caters for most sizes. Compatible with most CPAP, APAP and BiPAP machines . Note: Size depends on nose length. Measurement takes place from the base, where the upper lip meets the nose, till the tip of the nose. (See the attached diagram) (S) Small = 1 ~ 2 cm (M) Medium = 2 ~ 2.8 cm (L) Large = 2.8 ~ 3.5 cm