Radiator Valve Replacement Tails 15mm x 1/2" BSP (PAIR) The product is a pair of 15mm x 1/2" BSP radiator valve replacement tails, made of brass with a brass finish. It is designed for hydronic (hot water) systems and includes a thermostat. Manufactured in the United Kingdom, these timerless radiator valve tails are a reliable and efficient solution for controlling the temperature in your home. The fast delivery ensures that you can quickly replace your old or damaged radiator valves and continue to enjoy a comfortable and warm environment.