Tench Pressure Gauge & Quick Fill - Service Kit
This is for a service kit for the Tench gauge and quickfill for BSA and S200 rifles. If you are getting a leak or you are carrying out maintenance you may want a set of these.
There is a servicing video on the XTXair YouTube channel.
You are buying a service kit, which consists of a number of O rings, you are not buying an actual pressure gauge & quickfill.