Advantage:Made of zinc alloy material, it has the feature of stability, hardness, corrosion resistance, and wear resistance. Moreover, it is light and easy to carry outside. Square Socket Design:Designed with a square hole, it is highly compatible and can fit the holes of many tools as a wrench. Instruction:Easy to use, insert the valve key to the air vent valve of radiator and screw the valve for air venting. Application:These valve keys are very practical and widely used in radiators, faucets, plumbing systems, etc. Moreover, the square hole is very flexible and can also be used in the keyhole of various tools., Manufacturer: LAJHDCG