Zephyr B.N.A.E. (metric) screwdriver bits. Also known as French recess bits. 1/4” hex insert shank and 1/4” hex insert shank with ACR. Zephyr Phillips ACR insert bits feature special wing-face ribs grip screw recesses to reduce stripping and cam-out which can result in damage to the surrounding work piece. The name comes from the Bureau de Normalisation de l’Aeronautique et de l’Espace.