Purchasing CPAP mask parts is a cost effective way to increase the life of your mask.
After reasonable use, silicone cushions will start to become less flexible and will lose their “spring”. Usually the first sign of this is noticing that your mask leaks more and it is harder to get a good seal.
Your mask’s headgear will stretch and eventually loses its elasticity. Considering that headgear is used about 8 hours a night for every day of the year it is no wonder that it becomes less effective and worn. If you find that you need to tighten your headgear to get a good seal this may be a sign the headgear or cushion are at the end of their effective life.