Polished steel twist drill bits with uniform 3/32" shanks can be used with all quick-change or Jacobs chuck-style hand pieces. The smallest size is .50mm and they go up from there in .10mm increments to 1.60mm. Swiss made. (.50mm, .60mm, .70mm, .80mm, .90mm, 1.00mm, 1.10mm, 1.20mm, 1.30mm, 1.40mm, 1.50mm, 1.60mm)
I use these with my cordless Dremel tool to drill through sheet metal (my Dremel isn't powerful enough to go through thicker than 22 gauge Sterling). The 3/32" shank is too small so I wrap the shank a few times in masking tape to "thicken" it up so my chuck (collet) can hold it. Or you can get smaller collets for the Dremel. These shanks will fit most other drills.
Heather (Wildflower Native)
These were just what I was looking for, and fit well in my flex shaft.