This is a Whiteside straight bit, model 1083A, ground for general-purpose straight cutting, dadoes, and grooves. It and uses carbide cutting edges that resist heat and hold an edge far longer than plain steel.
Chuck it into a router table or handheld router to cut dadoes, grooves, mortises, and clean straight edges. The balanced bit runs true at speed, so cuts come out concentric and clean with minimal sanding afterward.
Whiteside Machine Company manufactures its router bits in Claxton, Georgia, and is consistently rated among the top-performing router bit makers in independent woodworking tests.
