DIN 911 hex key, long
Sometimes, screws are in difficult-to-access areas so handling them may be impossible due to lack of space. In these cases, long Allen keys allow for reaching nooks and crannies to tighten screws. They are also made of chromium-vanadium steel, which improves wear resistance, according to DIN 911 standards.
Chrome vanadium steel 58 CrV4 (1.8161)