Review on Screw Pressure Gauge for Spare Air by Tim Paolucci

It is fine and works well. I would give it 5* but it is so important to Spare Air that it shouldn't be added. It's like the famous horror story of a car dealership that sells you a car and asks if you want tires for it. This ensures that the reserve air is properly filled and pressurized. It's not necessary for emergencies (you've got what you've got for emergency climbing and knowing that doesn't change that), but it's certainly nice to know you've got 3,000psi to start with.