1 . Walter SST+ ½” Prentice are heavy-duty large diameter drill bits for use in portable drills, drill presses and magnetic base drills with ½” chuck capacity. Their extra hard tips allow for the drilling of many more holes between re-sharpenings. They are made with a cobalt blend for longer life. Drill Bit Specs: 31/32″ Drill Diameter, 3-1/8″ Flute Length, 6″ Overall Length; Walter SST+ ½” Prentice are heavy-duty large diameter drill bits for use in portable drills, drill presses and magnetic base drills with ½” chuck capacity. Their extra hard tips allow for the drilling of many more holes between re-sharpenings. They are made with a cobalt blend for longer life. Drill Bit Specs: 31/32″ Drill Diameter, 3-1/8″ Flute Length, 6″ Overall Length. Features: 3 Flats on shank prevent slippage inside chuck, Drills more holes faster, Exclusive point geometry eleminates pre-drilling, Special bronze SST treatment. For use on: Mild steel, Non-Ferrous metal, Stainless steel. ; .