Shop name:Chong Qing Shuo Yue Ke Ji You Xian Gong Si This is the very grade of HSS steel. True engineering quality. This set of drill pieces have been fully ground and heat treated for extra strength and durability. Fully ground bits are machined from a single bar and are better a normal rolled or twisted drill bit. They are also more expensive to manufacture. These have a long lasting working capacity and an aggressive 135 Degree Split Design. This set also comes with handy l carry case so you can keep organised in their and tidy positions. Starting at 1mm these drills increase in size in 0.1mm increments Hss 135 Deg Split Color: Silver Ground high speed steel (HSS) General for wood, metal and plastics Sizes from 1mm to 6mm in 0.1mm increments Package Contents: 51 x drill bit set 1 x Box (Color Random, can not color) Only the above package content, other products are not included. Note: Light and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.