6" 400 Grit Aluminum Oxide Non-Vacuum Hook-and-Loop Disc (50 Pieces) (23-622-400) by Mirka Abrasives. Mirka Gold is a durable product very well suited for sanding at high speeds. Gold is an all-round sanding material that can be used for many purposes. In order to achieve an optimal sanding result, the semi-open grit binding and special stearate coating are designed to prevent clogging and pill forming.