Heat Treated Carbon Steel - Excellent for Wood * Includes Hex Key and Installation Plate * 2 Mandrel - Saw Sizes3/4", 7/8", 1 1/8", 1 1/4", 1 1/2", * 1 3/4", 2", 2 1/2", 3", 3 1/2", 4", and 5" Fits 3/8 in drills.