The articulated ratchet is a variant of the standard ratchet that differs in the design of its head. This head is attached to the body of the tool by a joint that allows it to tilt at various angles, often up to 180 degrees, from the handle. The main use of this mechanism is when working in confined or difficult to access areas where it would be impossible to reach or move effectively with a fixed straight ratchet. This allows the user to fit the socket onto a bolt or nut and move the handle away from an obstruction, such as an engine or body part, giving the user plenty of room for actual ratcheting, i.e. moving the handle back and forth. Many knuckle ratchet models also feature a lock, which is a mechanism for locking the knuckle in the desired position. This prevents unwanted movement of the head when applying force and ensures more stable and precise work.