Many World War II-era German tanks utilized armored skirts (Schürzen) to make their thinner side armor more resistant to anti-tank rifles. Contrary to popular belief the German "Schürzen" were designed against kinetic (AP, APBC, APCBC) projectiles. The effectiveness of conventional AP projectiles was significantly reduced if they broke through a thin plate or dense wire net, because the projectiles become unstable in their trajectory and their tip would also be damaged. This method was very effective against contemporary light anti-tank weapons, like the Soviet 14.5 mm PTRD-41 anti-tank rifle and 45 mm M1937 anti-tank gun, the British 57mm Ordnance QF 6-pounder, and the US 37mm gun.