The No. 20 is a Quick Change Handpiece for use only with 3/32in (2.35mm) burs. A lever action on the the handpiece body is all that is required to change accessories.
It has a molded plastic front grip with tapered sides for easy and close handling, plus pre-lubricated ball bearings that do not require additional lubrication.
Exclusively for use with 3/32" shank burs. 5-5/8" long, 1-1/8" dia. (center), 3/8" dia. (front taper)