I have quite the collection of Forstner bits. You can tell the ones I use a lot because I have re-sharpen them countless times. I'm thinking about buying some new ones. I have a few that came with an extension. I can't remember where I got those. I do not want to buy the cheap ones at Lowe's or Home Depot. Where do you buy your Forstner bits? Where did I get the ones with an extension, they are really good quality. I use mine to speed up my hollow forms, my urns and more. Right now I have been commissioned an urn and 3 small cylinders for the ashes. They look like needle cases. I hollow one with the Forstner with the extension. That's what made me decide I need a new one! One cylinder will pay for a few. Thanks in advance. Aloha