The HYDRO-LIFT features a valve in its piston, which, in addition to user-optimized force support, allows infinitely variable positioning in the compression range. Controlled by a spring, the valve holds the position until a defined pressure, which is applied to the object by hand, opens the valve. The extension force is specified in such a manner that the gas spring does not extend by itself. Depending on the design of the HYDRO-LIFT, the hold function can be active across the entire adjustment range or in one or more partial ranges of the application. Unlike the gas-filled version, the oil-filled HYDRO-LIFT features are limited, rigid locking in the compression direction, thereby eliminating bounce. HYDRO-LIFT is used to safely fix the application, without the need to use a release mechanism. Possible areas of application are backrest and footrest adjustment of recliners, foot panels in hospital and nursing home beds, service flaps, or roof windows.