The Drayton TRV4 angled valve is A rated for efficiency by the European valve manufacturers association making it one of the most energy efficient TRVs available. It features a 15mm angle valve, 'Class I' rating, reverse flow, accurate liquid sensor, and non-stick internals. This product comes with an 18-month warranty. Drayton 0707260 TRV4 15 mm Thermostatic Radiator with Matching Lockshield Valve - White Trv4 white integral head 'A' rated for energy.