These circular discs are aluminum oxide grit with a no-load, zinc stearate coating for longer wear.
B/C-weight paper with resin-resin bond. All have a loop backing to attach to orbital sander plates that have a hook facing. The 5" discs come in two styles: plain or perforated (for dustless sanders).
Please check your sander for size and number of holes before ordering. All discs sold individually.