16356 Robinair Universal A/C Dye Cartridges with Four 1 oz. twist-on cartridges. Enough dye for 20 applications (OEM-approved and SAE-certified dye). Simple to use: Twist a cartridge onto the injector gun, hook up to the service port, and pull the trigger to inject the dye into the A/C system. Put your old lamp to use to spot the leak and you’re done.