Knurled rim knobs are made to obtain a firm grip. The small ridge patterns are rolled or cut into the material for a non-slip grip. They come in a wide variety of different styles and are often used on applications where the operator may be in contact with damp or wet surfaces. The knurled rim helps to prevent fingers from slipping to ensure positive tightening. They are also available in a handle form for use with a longer or larger surface area that requires using other directional movements.