Dremel 506CU 7/8-Inch Premium Metal Cutting Rotary Wheel Long life: At least 20x longer metal cutting life than standard Dremel rotary fiberglass reinforced cut-off wheels Won't shrink - wheels have constant diameter during use for a full-range depth of cut Durable: No wheel breakage saves time and cuts costs High performance: First Dremel rotary accessory to use a CBN grit for a longer cutting life