The FAG KM series standard right-hand locknut with metric dimensions locks bearings onto shafts or adapter sleeves so that bearings stay in place. It is a right-handed locknut with 12 threads per inch and is made of steel for durability and resistance to deformity under heavy loads. The locknut provides four evenly spaced slots on its circumference for use with hook or striking-face wrenches when tightening into place. The dimensions and materials of the locknut conform to Deutsches Institut für Normung (DIN) 981 and International Organization for Standardization (ISO) 2 982-2 standards for quality assurance.

Rolling bearings use rolling elements to maintain the separation between moving parts to reduce rotational friction and support radial and axial loads. These elements can be one of the following types: ball, cylindrical, spherical, barrel, needle, spindle, or tapered. All rolling bearings are open, shielded, or sealed. Sealed bearings are lubricated with oil or grease in the bearing factory, while open and shielded bearings are meant to be lubricated in place, with periodic reapplication of lubrication, based on use. The shield protects the working parts of the bearing from environmental debris that may be introduced and could reduce the ball bearing speed and lifespan. Rolling bearings are used in a range of applications from agricultural machinery to conveying equipment, robotics, dental equipment, elevators, rolling mills, ship rudder shafts, and aggregate crushers, among others.

FAG manufactures a variety of bearings that meet International Organization for Standardization (ISO) and Deutsches Institut für Normung (DIN) standards for quality assurance. Founded in 1883, FAG is based in Schweinfurt, Germany.