I have a couple of the Transair lifejackets, and I noticed their date had expired. Transair do sell replaceable gas cannistors for them, which although they come with instruction, I am a bit apprehensive to do the work myself. Theres a chance I will mess it up and they will activate in my face, or worse still, they wont activate in a real life situation (which I hope wont happen). No plans to fly over water just yet, so I need to think do I do a DIY replacement, or just buy new jackets and have a stronger peace of mind.