The twin body of each Cascade Twin Radiator Valve is made up of one thermostatic radiator valve and one lock-shield. The lock-shield valve is used to balance your heating system and the thermostatic head is used to regulate the room temperature. Numbered 1 to 5 you have easy control over the room temperature, ranging from 7°C to 28°C. Additionally there is a frost protection feature, so when the control head is turned fully clockwise (off), this allows the valve to open if the temperature falls below 7°C, preventing pipes from freezing in cold weather. We also provide a decorator's cap and full installation instructions for further convenience. These valves are designed and manufactured to a high standard both mechanically and aesthetically.