Review on Retrofit Fitting Adapter Kit for R12 to R134A AC Conversion, High/Low Fitting Port Retrofit 1/4’’ to 7/16''-20 UNF Conversion Adapter, Compatible with AC Air Conditioner Refrigerant R12 R22 to R134A by Corby Muin

The pins inside that are designed to push against stock Schrader valves were too long for my 1/4" R12 couplers (1988 Chevy K2500) .I couldn't use these adapters at all as simply screwing them onto the original fittings immediately caused a massive leak.Trying to tighten them further only bent the pin and made the leak worse.I don't feel comfortable going back but these do Connectors didn't meet my needs at all. In the end I settled on a rectangular set from Revain that fit just right.