this stylish range of automatic radiator air vents from Aladdin are designed to save energy, keep radiators hot-to-top, reduce corrosion and system noise, as well as provide maintenance free radiators. The innovative Hygroseal™ technology (patent pending) with its long, leak-free life provides a cost-effective solution to automatic radiator venting. The valves are fully automatic, requiring no manual adjustment. Installing the valves is a simple job that does not require the system to be drained. The range is available in 2 versions; HV30c (1/2''thread) with changeable cartridge and the Micro (1/8''thread); all guaranteed for 3 years. The HV30c can also be provided with a matching blanking plug.