1. The internal pin is connected with the upper knob to realize the adjustable function. When in use, CCW switch the knob to close the R1234YF coupler, fasten it to the AC service port, then CW switch the knob to lift the internal pin to insert and pull out the Schrader valve core slowly. Compared with the push to insert directly, this design can reduce the wear of the AC service port valve core by the internal pin, and ensure no refrigerant leakage when connected and disconnected 2. Snap lock quick interface at the bottom implements the quick function. Outside of the adjustable quick connection interface, there is an anti-slip knurled grip ring, and inside of the interface, there is an accurate snap lock with ball bearings design, which compatible with all mode of R1234YF service ports by quickly connecting and disconnecting. 3. The blue low pressure R1234YF quick connector, connects AC manifold gauge blue hose 1/4 inch Female parts to auto AC suction service port. And the red high pressure R1234YF quick coupler adapter, connects AC manifold gauge red hose 1/4 inch Female parts to auto AC discharge service port. Very easy to use. 4. Easy to install and use. 5. Material: copper