Drive Type Grease Fittings are designed for fast production line installation in untapped holes to avoid thread tapping costs. The hole size and shank dimensions are for reference use only.  Test applications should be conducted to determine the correct hole size, which varies depending on the type and hardness of the metal.  Drive Type Grease Fittings have a serrated shank, which facilitates the substitution of damaged grease fittings in old or oversize holes.  Although drive fittings grip securely, they are recommended for low and medium pressures.  Drive fitting tools are recommended to ease installation and prevent damage.