CMT 838.285.11 CMT Roundover Router Bit 5/16" radius 1/4" shank -Fatigue Proof® Steel- CMT router and boring bits start from solid bar stock steel. A hot drawing process pulls all the fibers of the steel in one direction resulting in extra strong and resilient bars. This provides a highly uniform steel to machine the bits from - CMT router bit bodies and shanks can withstand even the most demanding mechanical and thermal stresses, acting as perfect shock absorbers during cutting.