These radiator keys are made of quality zinc alloy, light and practical, durable and sturdy, not easy to break, easy to hold and turn, even after screwing in a few rigid valves, there is still no distortion on the key. The radiator key is useful for bleeding air from radiators. The ventilation key can be used universally and is suitable for most common radiator. Features - Color: Silver. - Material: Zinc alloy. - Size: 2.50X2.50X1.00cm/0.98X0.98X0.39inch. - Very strong zinc alloy material, workmanship, wide range of application. - Can improve the efficiency of the radiator and prevent noise from being generated in the radiator. - Prevents noise in the heater. Particularly easy to use. Does not require any additional expert help. - The ventilation key can be used universally and is suitable for most common radiator. - polished zinc alloy keys. For air vents to release air from water-filled radiators. Package list: 8 x Heater Bleed Keys