At this time, the aviation industry was making advancements in reducing space and weight by modifying fasteners, but was struggling with rounding of the fastener corners upon removal. The Navy sought Snap-on to solve this dilemma.

The solution, called the Flank Drive® Wrenching System, was issued two patents in 1965 and proved so popular that it spread throughout the Snap-on product line. Each hex point of the socket was curved to prevent contact with the fasteners’ corners and the angles of the sides were altered to improve flat-to-flat contact.