Quantity per package: you will receive 2 radiator keys, ideal for replacement and helping to prevent central heating system issues during the winter months. Measurement: the radiator key measures approximately 3 x 2.2 cm (1.18 x 0.866 inches). The inner square edge is 5 mm (0.197 inches) and the outer diameter is 8 mm (0.315 inches). One size fits most radiators on the market, making it easy to use and convenient for everyday home maintenance. Strong material: these radiator keys are made of high-quality zinc alloy, offering a lightweight, durable, and sturdy design. They are resistant to breakage, comfortable to hold, and easy to turn. Even after use on tight valves, the wrench shows no signs of distortion. Utility design: designed for ease of use, this lightweight and durable radiator key helps save effort. It is a practical and reliable tool for every household, built to withstand regular use without breaking or deforming. Wide applications: this radiator key is ideal for bleeding air from radiators, ensuring efficient heating performance.