Allows for quick and easy extended depth drilling applications. This extension adds 12 in to the drill tube length for any of our wet core bits. Features Designed to used with Milwaukee® premium wet core bits. Extends core bit drilling depth by 12 in. Apply anti-seize lubricant to threads before use. Designed to be used wet 57215. Milwaukee® Wet Core Bit Extension, Premium Grade, 4 in Drill, 12 in Length, Steel, For Use With: Diamond Premium Wet Core Bit