For simplifying the mass production process designers used in the gun's construction cheap types of carbonized steel without or with minimal use of rare and expensive nickel-, manganese- or chromium-added types of steel. Early version had two seats for the crew on both sides of a barrel, from 1906 they were replaced with an armoured shield. The shield had a specific design: an outer shield, with a big rectangular opening, and a smaller, inner shield behind it. The upper and lower portion of the bigger shield were folding during transport.