The life of a mask cushion depends on various factors such as how much you use it, how often you clean it, and the oil from your skin. We highly recommend inspecting your mask according to the cleaning and maintenance routine outlined in your mask user guide. The user guide supplied with your mask contains guidelines to help you inspect, assess and replace your supplies. Check for small tears or pinholes and anything else that might cause a leak.   Because the timing and reasons for replacing your mask cushion greatly depend on your mask, it's important to reference your mask user guide for specific details.