Chelsea Thermostatic Antique Radiator Valves These traditional Chelsea thermostatic valves are available in 3 different finishes. Polished Chrome • Antique Brass • Satin Nickel The sleek and stylish valves add the perfect finish to a traditional style cast iron radiator. Each valve has three rings engraved into the stem so that you can identify what temperature you have set. The top ring is set at 6 degrees (providing frost protection), the middle ring indicates 20 degrees and finally the lower ring indicates 30 degrees. Technical Specification: Turn temperature control Valve inlet : 15mm compression Radiator coupling: 1/2" BSP male thread Frost protection setting 3 beautiful finishes 5 year warranty from manufacturing defects Thermostatic .