Bosch 3 4 in Carbide Tipped Roundover Router Bit Pole Sander A: Use the included pin Shutters A: Use the included pin key to release the push button lock from the outside They are PVC and resist humidity requires little or no sanding before applying finish Compact ball bearing pilot – guides bit along edge of material shelves or stair treads Reinforced shanks – feature fully hardened and tempered steel shanks that provide ultimate durability Upgraded micrograin carbide – engineered for precise cuts and for long bit life Bosch exclusive heat treating process – provides hardness and withstands high temperatures Comprehensive line of bits – features hundreds of profiles for mortising