This quick coupler adapter can be widly used for most automotie air conditoner diagnostic AC manifold gauge hose service ports,1/4 inch male flare as well as 6-ball style coupler. One set for all. Design: This quick detachable fitting and 6 ball snap lock design make the opearaion easy. This kit gain a much better tightness and usage field. Blue and red ( low and high) switch separate the on/off button clearly. Installation: Connect the button to the vehicle's R134A service port and the copper adapter with the refrigerant hose, turn on/off the switch at top to turn it on/off. Kindly let us know if there are any doubts. Note: Installation guide not included, we strongly recommend you professional installation. Please check as much as possible to make sure the item is what you need. Tips: The product may be updated constantly ,Due To Different Batches, The Actual Product May Have Slight Differences Or Color Differences, Which Does Not Affect Use Colour:Photo Color Material:Metal Package