How to choose suitable gas struts?STEP 1. Measure the length of lid Distance from the hinge point to the edge of thelid. The Extended Length of Gas Strut ≈50% of the Lengthof the Lid. STEP 2. Weigh the lid Unscrew the lid from the hinges and use a scale to weight.STEP3. Calculate the pressure E.G. reading of 10Kg,1KG=10N, 10kg lid means that (G) equals 100N. If you are going to use 2 struts on the lid you can half the amount of pressure in each strut. How to Install Gas Struts?1. Open the lid to the position you required, mark a point at 1/3 or 1/2 to halfway from the hinge to the opposite side of the lid as the upper mounting point.2. The lower mounting point is often blow the upper mounting point.3. After installing the upper and lower brackets, just install the gas struts.If you feel it is too powerful to close/open, you can move the mount point on the lid towards the hinges' direction.If it is too weak, move the mount point on the lid opposites to the hinge direction.