We developed the M311 SPELTER knife in co-operation with members of forward air observation units, close protection teams and special air operations. Other members of the military and security community also contributed to its design. During the knife’s development, we focused on making use of their experience and requirements. Thanks to this unique co-operation, we had the chance to genuinely verify the quality of the chosen materials, design and general construction of the product. The knife was tested over a long period in extreme environments and various climates, including hot, dry and humid parts of Asia, as well as freezing areas beyond the polar circle.