This Smaller Hole Saw Arbor fits all our Tungsten Carbide Grit Hole Saws from 5/8" (16mm) Diameter through to our 1 1/4" (29mm) Diameter and comes with the standard 1/2" thread. The End on this Mandrel / Arbor has an 3/8 Hex fitting Also available with an SDS Shank In our Store. The main difference with these Holesaw Adapters is the fact that the Pilot Drills are Masonry Bits That means they have Tungsten Carbide Tipped Pieces welded into the tips This means they can drill through hard abrasive products And are designed to be used with a Hammer Drill. After All whats the Point Having a Hole Saw that can cut the Tough Stuff if the Pilot Cannot? This makes them perfect for Drilling materials like Brick, Marble and Concrete. Pilot Drills are 5/16 8mm Diameter with a 1/4" 6mm Diameter Shaft and are replaceable and available in our store. Notice our pilots have a flat milled on them so the hex grub screw can hold very secure. Our 5/16" special Spear Point TCT Tile Glass Drill also has a specifically designed 1/4" shaft. This means it will fit in any of our Adapters for drilling ceramic tiles without slipping. These Adapters are designed to take serious abuse and will outlast conventional tools. They can be used in Corded or Cordless Drills with or without Full Hammer Action. These Adapters were intended to be used in conjunction with our Tungsten Grit Edge Hole Saws. They can cut Tough Abrasive and Brittle materials like Brick, Masonry, Slate, Marble, Construction Materials such as Autoclaved Cement Board, FiberGlass, Composite Boards Chipboard, MDF, Laminates, Rubber Tires, GRP, CFRP, Hardwood Flooring, Laminate Flooring, Plasterboard / Drywall, Soft Resinous Woods and Hard Brittle Materials. For Drilling Deep Holes, Adapters attach to 3/8" Hex end with Hex Screw. Extensions not suitable for SDS fitting Arbors / Mandrels We are always looking for the next Amazing Product or latest inventions so don't forget to Sign up for our email newsletters You will be informed first of any new Products, Designs, Instructions, Videos or Inventions etc. Check Out Our Store I Guarantee You Will Find "Another Amazing Product" Click on any of the Images below to go to that section in our Store You might need to Scroll Up the page when you get there.