We have instituted a policy of marking all of our cloth & leather items with an indelible stamp of the letter S within a diamond. This is the wartime stamp of the Showa Steel Works, a company which produced WWII Japanese helmets. This stamp will appear in a hidden area so as not to destroy the display potential of a particular item, yet noticable enough for the potential buyer. Typically the underside of a strap, inside pockets of haversacks, helmet liner pads and so on will be marked. Marking items of steel and wood is a wasted effort because the marks can be easily wiped off chemically but items of leather & cloth are another matter.