From Karcher
Robust, premium backflow preventer (metal/plastic) for 3/4" and 1" hoses. Suitable for connecting to cut lengths of suction hose for garden pumps and high-pressure pumps for domestic use. The backflow preventer prevents the backflow of water and shortens the priming time. Includes hose clamp. Key Features Robust materials for a long lifetime. The non-return valve prevents the pumped water from flowing back and therefore shortens the re-suction time. For individual set-up of a suction hose kit