CK-507 Hammer A hammer is a medical instrument designed for testing reflexes and the nervous system response. Doctors use it to test the reflexes in people by softly striking particular areas on the body to cause the muscle to contract. Features: - Chrome plated hammer is extendable with pointed tip. - Head can be used in both horizontal and vertical position without unscrewing the handle. - Available with the telescopic range from 16.5 cm. to 37.20 cm. long.