For treating the surface of the bayonet, the part which connects an interchangeable lens to the camera, hexavalent chromium is the most commonly used material. At SIGMA, however, we instead opt for trivalent chromium, which is both more environmentally-friendly and safer. Compared to hexavalent chromium, the trivalent chromium we use is a more costly material, more difficult to process and manage, but it enables us to create products with improved quality and performance with a reduced environmental impact.