The most important will definitely be the quality of the tool tip. The tip of the wrench really needs to be very hard and very precisely machined to fit the screws perfectly, and to not wear over time. Unfortunately there are many bad quality tools on the market and the result can often be stripped screw heads and a lot of frustration and anger. As always, HARD tools are made to the highest quality, and that’s why we use high quality extra hardened tips on all of our wrenches. In addition the HARD Carbon Hex wrenches come with a hardened aluminum tip holder to further boost reliability.