67-134 LBs Lift Struts -- Fit the cover or door or lid which the SIDE LENGTH is more than 35 INCH. Very STRONG, NOT suitable for Window, Couldn't be compressed by HANDS. If you are not sure the item is okay for your project , pls Contact Us Before Purchsing; This lift support kit is for heavy duty lifts, please make sure your application cover weighs at least 30 pounds 15 Inch Lift Supports--2 pcs lift supports force: 134lbs (600N): If your door/lid is less than 20lbs, please choose less-pressure lift struts; If your project is about 20-65 lbs, you can just install ONE strut; If your project is between 65lbs-135lbs, then INSTALL both 2 struts; If your project weighs more than 135lbs, choose stronger-pressure lift supports or install ADDITIONAL lift supports 15 Inch Lift Supports--Keep the lid door/cabinets at 90-150 degrees, please check below description for adjust method. Special installation instruction is attached in the package, please check or contact seller for needed installing tips