A tension wrench is a simple tool used in the art of lock picking. It is typically made of metal or plastic and is designed to apply rotational pressure to the lock cylinder. By inserting the tension wrench into the bottom of the keyway, the user can turn it slightly, creating tension that allows the lock pins to be manipulated. When used alongside a lock pick, the tension wrench helps to align the pins within the lock. This technique is essential for successfully unlocking a door without a key. Mastering the use of a tension wrench is a fundamental skill for locksmiths and hobbyists alike.