Bosch 2609390038 Extension for Adapter with Key Width 7/16 inch - 11mm Hex Shank

This is a good solid piece of kit however, although I tightened the grub screw, I didn't tighten it enough and it fell out as I was drilling through a cavity wall with a Bosch hole cutter. I managed to extract the cutter but the screw was lost. I contacted the supplier (Campbell Miller) to purchase a replacement screw but was told that Bosch did not supply them. This surprised me as I can't be the only person this has happened to. Graham at Campbell Miller was very helpful providing the screw dimensions and I eventually managed to source replacements from China through E-Bay.

solid bit of kit ,been using for two years now and has proved essential at times to get in awkward places with large and small holesaws..holds the arbor solidly and runs centered

Highly efficient and durable. Works best with hole saws.