TRWD6 1/4” Insert Bits for #6 Tri-Wing® Recess. The Tri-Wing® bit, also known as Triangular Slotted, screw drive has three radial slots. Tri-Wing®, as the name suggests, is a screw with three ”wings” and a small triangular hole in the center. Tri-Wing® fasteners are becoming extremely common in automotive repair and appliance assembly.