Tiger Zirc 4. 5 inch type 27 depressed center cutting wheels cut faster and last longer so you get proven productivity at an exceptional total cost. The self-sharpening zirconia alumina grains retain a high cut rate throughout the life of the wheel while a hard bond delivers long wheel life for heavy duty applications. The flat profile of the wheel in combination with depressed center allows for a wide range of grinding angles (0-45). The . 045" wheel thickness is ideal for cutting tubes, bar stock, and large cross-sections with a right angle grinder. The small 5/8" - 11 nutted metal hub reduces gouging of the workpiece and allows for 30% more usable surface area of the wheel in addition to providing quick spin-on, spin-off changeover of a standard hub. These wheels are designed for hardcore Metal Fabrication professionals who need a high performance solution when cutting steel, structural steel, and iron.