Koehn sold fighting knives under the AOK Knives label. This Knuckle Knife is a modified US Mark I Trench Knife. The knife has a cast aluminum handle with the inner ear removed and the body painted in black & green camo. On the top of the grip it is stamped AOK KNIVES NO.7 and on the side in a raised casting is BY ARMAND. Blade is a 7 inch version of the 1918 Mark I Trench Knife blade. The leather scabbard is riveted in 5 places, painted in black & green camo also, and marked AOK KNIVES HAND CRAFTED BY ARMAND KOEHN. Reference for this rare specimen is Adrian Van Dyk List #114, #165.