Resistant to deformation and abrasion. Can work at a much higher load without damaging bits or screws. 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. 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: T10, T15, T20, T25, T27, T30, T40, T45, T50 keys. Packaged in a practical blister pack.