SPDB is a small 75mm disc made from Finixa sanding material available in different grains and dimensions. This solid synthetic carrier makes not only the sanding materiel very solid, but also insensitive to liquid and atmospheric humidity, no loss of quality during stock. he back has a velcro system. The aluminium oxide grains are reinforced by heating up to 1200°C (blue fire process) and are open coated glued with two glues, finished with a white sterate coating that ensures that the sanding material (resin) cannot “clogg up”.