Review on MASTERCOOL 90262 Manual Shut Off Adapter by Bryan Fisher

Bought these for 3 reasons: 1. Allows me to drain the manifold lines and sensors before replacing them connect to the HVAC system. I simply open the manifold valves and draw a vacuum on the unit, then close all the valves before connecting them.2. Allows me to prevent air and moisture ingress when I switch the charge hose from the vacuum pump to the refrigerant tank. I know most techs just break the filler plug on the manifold to allow the refrigerant to fill the system and force the air out. However, this practice leads to loss of refrigerant and the risk of frostbite on the hands. Closing the inflation hose valve is better.3. R-134a quick disconnect manifold hoses usually have check valves on the fittings. The old R-12/22 hoses don't. With this set I can add valves to my old instruments. I also have adapters so the yellow fill valve can be used on hoses designed for R-12/22 or R-134a systems.