Pack of 10. The HV30C self-bleeding radiator valves save energy, keep radiators hot-to-top, reduce corrosion and system noise and dispense with the use of radiator keys. Automatically Bleeds Radiators Ideal for Landlords & Homeowners No Manual Purging 5 Year Manufacturer's Operating Guarantee Product contents: 10 x HV30C autovents, 1 x U-keys and instructions. Specifications: Fits both radiators and towel rails with a ½” BSP fitting. BSRIA tested.