AC Oil Dye Injector, R134A Compressor Oil Injector Kit with Snap Quick Coupler, 2 OZ A/C Injection Air Conditioning HVAC Tool with 1/4" SAE Male and Female for R134a R12 R22 Refrigerant System

This thing worked great. Had not used one previously and seems well made

Works as directed fitting are good quality

Easy to use. Inexpensive.

This is a fine choice if injecting oil or treatments is something that is relatively uncommon for you: it functions, injects without leaks (mostly... see below), does not waste refrigerant, and the 2oz size is a a solid middle ground. If you inject treatments frequently, you might want to consider an adjustable injector from a "premium" brand like Yellow Jacket or Nu-Calgon. I personally had to inject 4oz when I tested the product, so I had to open it up to refill. 2oz is exactly to the bottom of the threads inside, and opening up the injector while connected was not an issue, assuming you follow good practices for purging air. Now, the major problem. The hose section attached is cheap. Really cheap. It's the kind that comes with no-name vacuum pumps, manifolds, and on automotive gauge sets. After two uses, it started to blow back a small amount of vapor refrigerant from the swivel head unless the hose was positioned just right. Luckily, the design allows you to remove the cheap hose (and the port it is attached to) and swap it out for either a better one or just a regular male connection (like the schrader on the top). This would let you attach something like a known-high-quality valved length of hose.

WELL BUILT SHOULD LAST ME THE REST IF MY LIFE UNLESS I LOSE IT. WORKS VERY WELL NO PLASTIC TO BREAK... THE ONLY THING THAT SHOULD WEAR IS 2 O RINGS.... AGAIN VERY WELL MADE ALL ALUMINUM AND BRASS