A type of cylinder which, when the key is inserted, pushes down four to six pins to their correct positions. Only then will the cylinder turn, opening the lock. An incorrect key will either push some pins too far, or not far enough , and the lock will not open. Pin cylinders may also be replaced when needed. The looped portion of the top of the padlock which swivels open and closed.
Some models offer different shackle sizes to accommodate door hardware.