1Designed to Prevent Damage: This tool kit features seals that are sized smaller than the gland hole, which greatly reduces the potential for damage to the unit. 2Wide Range of Sizes Covered: The hydraulic cylinder piston installation tool includes three sizes for installation of any rod seal from 0.87 inches for a wide range of uses. 3Small: U cup installation tool fits 22 to 40mm (0.87 in to 1.57in Rod) cap holes with a maximum cross section of 6mm. 4Medium: Piston rod seal U cup installation tool fits media gland holes with rod diameters of 40 to 70mm (1.57in to 2.75in Rod) with a maximum cross section of 8mm. 5Large: The rod seal u cup install tool fits large gland holes with rod diameters of 70 to 165mm (2.75in to 6.49in Rod) with a maximum cross section of 10mm.