This Hozelock 2181 Non-Return Outdoor Tap Connector is an all-plastic double check valve, which connects to outside taps and prevents backflow into the mains water supply.
Made from high quality materials for a long leak free life, it is suitable for all 1/2 inch and 3/4 inch BSP taps.
Specifications:
Screw Thread: 1/2in BSP (21mm), 3/4in BSP (26.5mm).
Connection Type: Male.