Easily tackles a range of sign making applications. Flatter bottom prevents peaks in routed letters. For use with plunge router. Twin fluted. Compatible with Rockler Interlock Signmakers Kit (sold separately) , as follows: 3/16” compatible with 1-1/2” kit; 3/8” router bit compatible with 2-1/4” kit; 5/8" router bit compatible with 3-3/8" kit. 1/4" shank.