They feature a high quality external drive spring and a heavy gauge all bolted together frame

4-Way Valve Tool

but at the same time want a quality product reliable over time

For oils and ATF up to SAE 40 weight

Milton S-1093-4 1/4" FNPT In-Line Check Valve Couples S.S They feature a high quality1 4" FNPT In Line Check Valve 1 4" female national pipe threads on both ends Valve opens at 3 pounds per square inch Maximum operating pressure of 250 pounds per square inch Flow rate of 12 cubic feet per minute Maximum operating temperature of 450 degrees Fahrenheit 1 4" FNPT in line check valve is designed for piped systems to prevent bleed back of pressure material into air supply system. 1 4" FNPT on both ends. Has a maximum pressure of 250 PSI