Even if you take immaculate care of your mask, wear and tear happens. Over time, your mask cushion will accumulate grease and develop flaws that prevent it from forming a perfect seal. Don't buy a whole new mask! Simply swap out the cushion, saving yourself a bit of money and preventing unnecessary waste. This N30i cushion is directly compatible with the N30i mask frame, but you can also place it in the P30i mask to transform it into an under-the-nose mask. For maximum convenience, sign up for our Sleep Club! We will ship your supplies exactly when you need them.