Check the listing for details. 4PCS Diamond Bits for Stained Glass Grinder, Portable Grinding Accessories. Condition: New. Listed at 25.26 USD. Diamond Grinder Bit Set is made of brass core+double-layer electroplated diamond surface, sturdy and durable, not easy to fall off, with a longer service life. These diamond drill bits with standard frosted design reduces shaft jamming and does not adhere to the grinding machine shaft, resulting in smoother operation.