Review on 🛠️ Premium 2 Inch Sanding Discs Assortment Pack - 100 Pieces, 80-3000 Grit Sandpaper | High-Quality Drill/Grinder Tool Attachment with Buffering Pad by Alejandro White

.235 inch diameter shank. (6mm) while the shafts that fit on a standard die grinder are .249" in diameter, so you really have to rotate the collet to get it to work in a die grinder. Of course it is perfectly suited for a drill chuck. As mentioned in other reviews, most disc grains are unidentifiable on the back and the front faces are very similar, especially on the smaller grains. I should have read the description better because in this particular set there is a significant jump from 240 grains to 600 grains. Ideally, the set also includes 320 and 400 grit. The soft foam pad works well for sanding external contours, but the discs are flexible enough for sanding internal contours. Good set for the price.