I haven't measured - my test is to pull the hose off the cover cap and put my thumb over the hose. If I can feel suction, we're good. Also blow through the hose to check the valve, suck back -if you get air, replace the valve. They last various amounts of time. Last set I got from NAPA have lasted a good while. The ones that come with the kits may last a season, may not. Since you started with a kit, I'd go get two good ones for spares and have them ready.