Aggressive, replaceable self-feed spur for efficient rough-cutting of holes * Unique cutting geometry and open tooth design for more sharpenings and longer life * One-cutter design on even the smallest bits for improved efficiency * Flat sided, 7/16-inch ball groove joint for quick changes and minimal slippage * Includes 5-1/2-inch extension, 1-, 1-1/8-, 1-1/4-, 1-1/2-, 1-3/4, 2-1/8-, and 2-9/16-inch self-feed bits, replacement parts, and kit box