Carbon Steel,Stable and not easy to break,safe and,not easy to wear. Contains 13 screwdrivers,8 of which are flat-blade screwdrivers of different sizes,0.6/0.8/1.0/1.2/1.4/1.6/1.8/2.0mm and 5 crossing- for head screwdrivers of different sizes,1.2/1.4/1.6/1.8/2.0mm. Has a - design,which makes it very suitable for repair work of various small objects. Not only suitable for watch repair,glasses repair,jewelry work,but also for the installation and removal of various miniature screw buckles. The size can be quickly identified from the appearance,and you can easily operate the screwdriver.