The Zephyr spanner is a security profile with two rectangular pins, otherwise known as ”snake eyes”. The spanner bit is little used in trade and industry. The advantage of this profile is the surface of the screw head, which is broken only by the two small rectangular pins and is otherwise solid. At the same time, this profile prevents over-tightening of the screw. Force transmission is associated with high stress concentrations. However, due to the two pins, there is a lower stress on the individual faces. The spanner profile is not suitable for transmitting high torque.