Auto-Guide Hole Saw Arbor anchors and aligns for improved drilling. An extra strong spring increases tension for added stability and prevents surface "skating". The 1 3/8" retracting guide pin allows you to drill deeper and through thicker material. The Auto-Guide™ carbide drill tip penetrates surface for improved anchor and drill guide. Features the 5/8-18 industry standard thread for hole saw compatibility. The 6-Flat hex shank offers secure, non-slip drill chuck grip. Fits 3/8" or 1/2" drills.