Spring valves have a little spring inside and it allows you to push and turn so the inside bit pops up for inflate (where it only lets air in) and then you can push and turn so the inside bit stays down for deflate (where it only lets air out).
At the end of the pump hose, there’s a little bayonet style fitting. You push and turn to get that Screw-On Spring Valve Adaptor attached to the end of the pump hose. Then you can screw it on to the Spring Valve till it’s nice and secure.
If you look at the inside of the Screw-On Spring Valve Adaptor, it’s got a little plastic rise in there and what that does is push the valve back down halfway. This allows some air to be coming back up through the tube for the pressure gauge to work.
Don’t be alarmed if at first you think your pressure gauge is not working. The pressure gauge typically doesn’t start working till about 1 to 1.5 PSI. So you need to have the kayak fairly firm before you get a pressure reading.
NOTE – you need to use the Screw-On Spring Valve Adaptor to get a pressure reading, not the push-on adaptor.