Review on XOOL 62-in-1 Precision Screwdriver Kit - Complete Electronics Repair Tool Kit for Mobile Phone, Smartphone, Game Console, PC, Tablet - Magnetic Driver, Flexible Shaft, Extension Rod included by Brandon Rogers

I don't know what the bits are made of but very soft. I needed T2 and T3 bits for a small repair that involved loosening and then re-tightening about 20 screws. I'm very careful with these very thin bits, they don't have much available surface area after all. However, despite my very (very) careful use, you can see that the bits are almost useless now. The edges are warped and the edges are badly damaged. I think I got what I paid for :)