This brand new rotary tool kit by WECHEER is the most powerful unit on the market by far. It has a 30,000 RPM 1/2 HP motor that is reversible. The 42" flex shaft has a ball bearing design with a 4.5mm inner shaft. The unit is equipped with their new 1/4" chuck-type handpiece. It will take any size bit or burr from the very smallest all the way up to a 1/4" shank without fooling around with collets. There is also a variable speed foot control in the kit. NOTE: If you are wanting just the new 1/4" chuck handpiece, order #335129. It will fit any of the large size WECHEER units as well as Foredom, Pfingst and Mastercarver rotary flex shaft tools.