In March, 1945 the peninsula of Hel, which is now a part of Poland, was German and cut off by Russian troops. The only way to get mail to the rest of Germany was by boat, and the safest way was by submarine. This stamp was issued for that purpose. It's very rare,and I had it framed in a double gilt frame using conservation glass. The outer dimensions of the frame are 4.5" X 5.5". It's a beautiful thing, and tells quite a story. Please feel free to ask any questions you might have. Free shipping is within the lower 48 states.