Product: Exhaust Valve Key. Material: zinc alloy. Size: as shown in the picture. Features: 1. Clean the radiator: Older radiators tend to make unpleasant noises. Regular bleeding using the heating ventilation key protects your hearing and improves heating performance. 2. For all standard heating valves: The heater exhaust key has a square socket of 5 mm. With this, you can quickly and easily drain almost any heater. 3. Shatterproof material: Thanks to the special zinc alloy, the radiator ventilation key is the long, faithful companion of the toolbox. Our silver heater ventilation keys are anodized to make them corrosion resistant and extremely durable. 4. It can also be used in closed conditions: this is not a problem if your heatsink is not well installed. Our heating keys are small and compact. This allows you to ventilate comfortably at any of the smallest angles. 5. Easy to use: Simply place the sturdy exhaust key on the valve, gently rotate it and flip it over. The package includes: 3pcs/5pcs/10pcs. Notes: Due to the lighting effects and angles, there is a color difference in the product, please understand. Due to manual measurement, there is tolerance in the product size.