EZ-Ject is designed for mineral oil, PVE, polyol ester and alkyl benzene lubricant systems. The kit eases injection of fluorescent dyes into refrigeration systems without the use of additional refrigerant. The operator attaches one connection and then turns the handle to inject the dye. Suited for small-to-medium systems, each dye cartridge treats up to 2 gal of lubricant or 25 lb of refrigerant. A built-in check valve prevents the backflow of dye or refrigerant and eases storage of the hose/cartridge between jobs. It also prevents dye leakage and contamination.