Check the listing for details. 3 inch Quick Change Roll On/Off 36 Grit Locking Aluminum Oxide Discs -50 Pack. Condition: New. Listed at 28.25 USD. Blue Dot Abrasives manufactures industrial quality quick change discs in the United States for all your sanding and grinding requirements. Industrial quality 3" 36 grit Aluminum Oxide abrasive discs with the proprietary "Blue Dot" quick change locking system insures that the male locking screw is always secure to the backing on the disc:Heavy X/Y weight polyester cloth backing provides long life for deburring, stripping, cleaning, sanding, grinding, leveling and polishing.Roll Lock screw on mechanism fits any standard roloc, T-3, Type 3, Type R or roll-on back-up pad.Maximum RPM: 20,000 for use on a drill or die grinderAlso available in other grits and sizes. 50 discs per pack.Blue Dot Abrasives is a division of Blue Dot Laser. Trust an American manufacturer that has been in the abrasive industry for over 35 years with your sanding & grinding job. 100% satisfaction guaranteed.