Review on 🔧 Boltigen R134A Self-Sealing Can Tap Valve Refrigerant Dispenser Tool with Tank Adapter for 1/4 and 1/2-inch AC Freon Charging Hose - 1/2 Self-Sealing for Improved SEO by John Maskirta

I bought this along with a set of Pittsburgh and R134A Johnsen gauges that I bought locally. At first it didn't work. Then I realized that the 1/4" to 1/2" hose adapter had a standard Schrader valve installed to prevent anything from leaking out of the can. I closed the jar, unscrewed the schrader valve and reconnected it. It worked great with no leaks. If you buy one, remember to remove the valve (if necessary). You save yourself the confusion I had for not paying more attention.