This attachment allows you to control the water flow and pressure of your professional Karcher pressure washer at the trigger gun with a simple turn of the servo control. This attachment allows you to control the water flow and pressure of your professional Karcher pressure washer at the trigger gun with a simple turn of the servo control. Suitable for Easy!Lock pressure washers with a flow rate of < 750 l/h. Compatible with: HD 7/10 CXF HD 7/16-4 ST HDS 6/10 C HDS 6/10-4 C HDS 6/12 C