The military valve used on inflatable rafts and other watercraft is a very durable and dependable unit that's been used for years. It's especially found on older boats. Replacing the valve itself is pretty simple; just six screws hold the valve in place. However, generally the valve is installed in a recessed boot. Replacing a boot is a pretty major repair job. In this video NRS Repairs goes over all the steps for repairing and replacing military valves, including replacing a boot.