This is the replacement cushion for Respironics's TrueBlue Gel Nasal CPAP mask. Cushions lose their effectiveness over time, so you'll want to have replacements on hand.
TrueBlue CPAP Mask
The TrueBlue is designed to be a loose fitting and comfortable nasal sleep apnea therapy mask. The mask comes with a high performance, ergonomically designed gel cushion.The cushion features Freeform Spring technology: a flexible spring connects the gel cushion to the mask's frame, so that the mask can move while you toss and turn without affecting the quality of the cushion's seal. Made of a soft gel surface, the cushion won't give you any facial abrasions, allowing you to wake up refreshed and symptom free.
Make sure to pick a cushion that corresponds with your mask size -- large with large, small with small, etc.