Heavy duty aluminum construction . Injects dye or oil into R-12 or 134a systems. Refillable, any dye or oil can be used . Easy twist injection system. Precise injection control Heavy duty aluminum 2 oz refillable dye / oil injection system. To inject dye or oil, simply connect the injector to the low side of the A/C system and twist the handle until you reach the desired amount. The injector hose comes complete with a R134a coupler and Auto Shut-off Valve Adapter for 1/4FL systems. Injector easily allows the user to inject any dye or oil into any R-12 or 134a system.