The Mastercool 53134 Refillable Dye Injector (R134A Auto A/C System) with the R134a 13mm connection and 2 ounce bottle of concentrated A/C dye, enough for up to 25 applications. To inject the oil or dye, 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 1/4"FL systems. REFILLABLE DYE INJECTOR with (R134a 13 mm Connection) and 2 oz Bottle of Concentrated A/C Dye (25 Applications).