You will need to purchase a Re-Arming Kit 
Depending on your requirements these contain:
Please remember these components need to be specific to each life jacket make and model.
Checklist:
Contact us for more detailed advice, we are always happy to help: service@seasasfe.co.uk or +44 (0)1983-282388
Shown in the two photos above, a manual mechanism (left) and an automatic mechanism (right)
These were received by our servicing department in some of the worst conditions we have seen, scarily this is a common occurrence and we see life jackets on a daily basis which have not been properly looked after, this is why we are so enthusiastically promoting our service points as such a valuable and important service.