Double-End Screwdriving Bit. Deliver Both Speed And Convenience By Combining Screwdriver Bits In A Durable One-Piece Design. These Industrial Quality Bits Are Manufactured To Withstand The Same High-Torque As Other Century Power Bits. Do Not Place Double Ended Bit In Bit Holding Screwdrivers, Power Bit Holders, Or Quick Change Adapters. The Retaining Ring In The Both Holder Is Designed For Insert Bits Only.