The Milwaukee® 1.25" F - 5/8" M Bit Adapter allows bits with smaller threads to be used with the MX FUEL Handheld Core Drill. The bit adapter is included in all MX FUEL Handheld Core Drill kits. This adapter helps ensure that most common core drill bits will be compatible with the MX FUEL Handheld Core Drill. The adapter has a designated storage place in the hard case to help users keep everything together.