Disposable cartridges come pre-filled. Compatible with all A/C systems . (6) .5 oz cartridges. Great for diagnostics, too. Nothing is easier! Service multiple systems with just one connection per system EZ-Ject cartridges provide the fastest, easiest and cleanest way to add Fluoro-Lite dye to multiple air-conditioning and radiator systems, with only one connection per system. The best method for preventive and programmed maintenance.