An armlock in grappling is a single or double joint lock that hyperextends, hyperflexes or hyperrotates the elbow joint or shoulder joint. An armpit lock can be useful; it will immobilize an opponent and pin them on the ground. An armlock that hyperextends the elbow is known as an armbar, and it includes the traditional armbar, the shoulder triangle armbar, and the shotgun armbar. An armlock that hyper-rotates the arm is known as an armcoil, and includes the Americana, kimura, and omoplata. Depending on the joint flexibility of a person, armcoils can either hyperrotate only the shoulder joint, only the elbow joint, or both the elbow joint and shoulder joint.