Adapter Extension with 3/8" Hex Ends Attaches to Hole Saw with Hex Screw allows Drilling of Deep Holes Free Hex Key to Tighten Hex Screws Suitable for any Adapter with 3/8" Hex Shaft This Mandrel Extension fits all our 3/8" Hex End Arbors see other listings for 7/16" Hex. These Mandrel Extensions 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 with a 3/8" Chuck. When used in conjunction with our Tungsten Grit Edge Hole Saws, Deep Holes through Concrete and Cavity Walls are possible. For Drilling Deep Holes, attaches to 3/8" Hex end with Hex Screw We are always looking for the next Amazing Product to sell or latest inventions so dont forget to Sign up for my 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 The Important Stuff !!! We are a US Shipper based in Florida FL 34470 Everything we sell we have in Stock - We ship Fast within 24hrs. We aim to ship on the same business day if ordered before 1pm Eastern We Ship Free within USA using USPS First Class or Flatrate averaging 2-3 days. We will ship anywhere in the world USPS First Class Package International International Shipping 7-14 days subject to custom delays in your Country. If you are happy with our service please tell a friend If you are not please tell me, I will fix it if I can. We want your repeat custom Ships Fast From Florida USA