Product Review

Included: 
Impeller: 3x12mm, 5pcs; 3x15mm, 5pcs; connecting rod, 1pc  
Grinding burr: cylindrical shape: 3x6mm, 3x8mm,5pcs for each;rounded cylinder: 3x6mm,3x8mm,2pcs for each(Grit 60)
T shape E needle burr: 3x6mm, 4pcs(Grit 60)
Fine sand shape burr: 3x6mm 6pcs;Needle:2pcs(Grit 150)
Diamond Disk: 20mm 2pcs; 30mm 2pcs, with 2pcs connecting rods.
Great for filing glass, ceramics, tile, brick,fiberglass, stone, rock carbide, gold, platinum, silver, metals, and anything with a hard surface. Also fit and easy to install on Dremel rotary tools 4000,4200,8220,3000
Notes:
  Please try to replace the collet fit when these carving bits do not fit in your Dremel rotary tools!
Please add enough water and use eye protection! 
The grinder speed should not be too high, please adjust the electric grinder to 20000 RPM below and then the cut rods should be installed. High speed will lead to fracture of the rod.
Different shapes of diamond grinding head show that they got different usages, which makes them different from grinding wheels. The diamond grinding heads are cylindrical, elliptic and conical. The shapes are designed in conjunction with the processing of work piece shapes, which can't be manufactured by wheels. So when the wheels are not workable, the grinding heads come into use.
Still the grinding heads can be used in abrasive grinding features like: grinding, polishing and milling products. We all know that diamond is the one of the most hardest materials, which means the diamond grinding heads have the characteristics like Diamond, so it is often used in high hardness alloy, or non-metal super hard materials. So it's usages are different and special in comparison with general wheels or other metal wheel of grinding tools.