These flags are a 110g/m2 knitted polyester blend material and are 3'x5' (3 feet by 5 feet) in size and have strong metal grommets and double-stitched lines.
The straight-armed Balkenkreuz, which is a stylized version of the Iron Cross, was the emblem of the World War II Wehrmacht and its branches: Heer, Luftwaffe, and Kriegsmarine.
These particular flags were placed on vehicles so that German planes could tell where the German front line was. It was used for a very short time by German "SS-Totenkopf" units on the Eastern Front, but soon abolished because it was too noticeable by the enemy. The Germans did, early in the war, use signal drapes to identify German armor for the Luftwaffe, and had loops on all four corners making them suitable for fixing on tanks and even on the front deck of warships.
Photos exist with what appears to be Balkan Cross German Vehicle drape being used on the Eastern Front during 1944, and there are reports of its use during the Battle of the Bulge in 1945, both late in the war. Since most Allied troops picked up the majority of their souvenirs at the end of the war or immediately after its end (it is unwise to carry items looted from your enemy when there is danger of being captured yourself), the exact extent and use of this drape is hard to determine.