This MIBRO 5-Piece 5 in. 120 Grit Hook and Loop Sanding Disc Set features an 8-hole design for heat dissipation and dust extraction, designed for use with orbital sanders. The hook-and-loop backing enables quick attachment and removal of discs, so that you can get the job done faster. Made from aluminum oxide and ideal for use on hardwoods, metal and fiberglass. Aluminum oxide has self-renewing properties that breakdown under the heat and pressure of continuous sanding to create new sharp edges. Please note, the 5 in. backing pad is sold separately.