High-quality gas struts, such as original Stabilus LIFT-O-MAT units, are engineered to last anywhere from 3 to 7 years (or typically between 30,000 to 50,000 full compression cycles), depending heavily on environmental exposure, operating temperatures, and frequency of use. Over time, microscopic nitrogen gas leakage past the internal dynamic seals causes a gradual loss of lifting force, resulting in sagging tailgates or lids.