Pack of 2 solid brass keys for bleeding air from domestic radiators. Improves efficiency of boiler and overall system, ensuring even heat distribution and saving money on hot water bills. Fits most domestic radiators with square valves. Silverline offers a comprehensive range of tools for home, garden, and workshop use. All Silverline tools come with a lifetime guarantee for hand tools and a 3-year guarantee for power tools. Silverline tools are tested to comply with the latest quality and safety standards and are manufactured in factories that adhere to environmental and ethical standards.