Aluminium oxide cloth. Spiral glued to cotton backing tube. Ideal for sanding curves and bends. Compatible with all 90mm bobbin sander drums. Includes 13mm, 19mm, 26mm, 38mm, 51mm and 76mm bobbin sleeves. Aluminium oxide cloth. Spiral glued to cotton backing tube. Ideal for sanding curves and bends. Compatible with all 90mm bobbin sander drums. Includes 13mm, 19mm, 26mm, 38mm, 51mm and 76mm bobbin sleeves.