3M 28845 Hookit Interface Pad, 3 in x 4 in, PK10 G5127544 TOUGH CASE(R) Container Primary Material TOUGH CASE(R) Container Primary Material Application ISO Code O Number of Drill Bits 21 Shank Type Machining Straight Web Construction Tapered Drill Bit Case Type Box Impact Rating No Drill Bit Point Type Conventional Standards Not Rated Material Grade Machining General Purpose Package Quantity 1 Basket Hitch Capacity @ 30 Degrees 8 They attach to a compatible hook and loop backing pad on a power sander to reduce the time it takes to refresh a disc or change grits so they're a good choice for applications where the disc is changed out before fully worn