Review on DASBET A/C Oil and Dye Injector with Quick Coupler, 2 OZ Hand-Turn Screw-in AC Coolant Filling Tube Injection Tool, 1/4 inch SAE Connector for R410A, R134A, R22, and R12 by Ben Swett

I bought this tool to add some oil to my car's air conditioner. I replaced the A/C condenser and had to add some oil to the system which I had already drained. After adding oil to the tool, I connected the tool hose to the system and just slowly twisted the end of the tool to add oil. When the pen reached the bottom, the oil was added. That's all. Zeb