The shank of the mandrel must match the size of the power tool collet or drill chuck, and the pilot diameter must be compatible with the size of the cartridge roll.
3M 45120, Cartridge RoII Mandrel, 3/32 in x 3/4 in x 1/4 in, 7010328349
$4.11
Factory Stock, 7-10 Day Leadtime
3M Cartridge Roll Mandrel is a tool attachment that holds an abrasive cartridge roll (sold separately). Together, the mandrel and cartridge roll enable the user to grind or finish hard-to-reach areas of a workpiece, such as angles and curves. The mandrel attaches to a rotary tool such as a die grinder or drill, and comes in different sizes to fit a variety of cartridge roll sizes.

Dynabrade 11684 Dynabelter Contact Arm Assembly 4" DIA X 5/8" W., 40 Duro Serrated
3M 87261, Scotch-Weld Epoxy Adhesive DP100, Clear, 400 mL Duo-Pak, 7000121318, 6/case
3M 20227, Scotch-Seal Metal Sealant 2084, Silver, 5 oz Tube, 7000046343, 36/Case
3M 33501, Sanding Respirator, 03201, 7000120129, 2 per pack
3M 45714, Cubitron II Hookit Cloth Disc 947A, 120+ X-weight, 3 in x NH, D/F 3HL, Die 300BE, 7100113113
Dynabrade 64404 36" W x 60" L (914 mm W x 1,524 mm L) Metal Capture Downdraft Table, 230 V (AC), Side Exhaust
3M 19764, Utility Cloth Sheet 314D, 9 in x 11 in P320 J-weight, 7000000352
Standard Abrasives 840038, Quick Change Surface Conditioning GP Disc, A/O Medium, TSM, Maroon, 3/4 in, QS75KM, 7000121647, 50/case
3M™ 07011, Supplied Air Respirator Hose W-9435-50/07011(AAD), 7000005373, 1 EA/Case 
