Resistant to deformation and abrasion. Hardened working parts. Chamfered edges enable quick adjustment of the key to the screw. Made of chromium-vanadium steel, protecting against mechanical damage such as corrosion, abrasion or oxidation. Ball end enables the key to be tilted to 25° degree from screw head.Optimized hardness of HRC 52-56. The set is equipped with a compact clip made of high quality PVC with partitions marked with dimensions, making it easier to remove individual key and store them. The set includes: 1.5, 2.0, 2.5, 3.0, 4.0, 5.0, 6.0, 8.0, 10.0mm keys. Packaged in a practical blister pack.