Foredom Straight Split Type Sandpaper Mandrel, 1/8 inch Shank, Style A-M26. 3/16" head diameter 3/4" slot length 1/32" slot width. 2-3/8" overall length. 20000 RPM Max Speed. Sandpaper, or split mandrels, have a "split" above the reinforced base allowing the user to wind sandpaper, polishing cloth or other abrasives around the gap. These mandrels come in straight and tapered styles and are generally used to sand in tight spots. The straight version is good for finishing smooth surfaces while the tapered offers access to undercuts. Maximum and recommended speeds depend on the type and size of accessory as well as the mandrel in use. The ratings we publish for our mandrels are based on a 1" overhang with an accessory that weighs under 1 gram and is smaller than 1/2" in diameter. As a general rule smaller accessories and mandrels can be used at higher speeds than larger accessories and mandrels. It is a good idea to follow the recommendations that come with both the accessory and the mandrel you are using.