The most beautiful and widely collected of all U.S. Revenue stamps to license hunters are officially known as Migratory Bird Hunting and Conservation stamps. Each design is selected in an annual competition with the proceeds from their sale directed to preserve waterfowl and wetlands. Due to their high face value and small print runs, the availability of these fascinating, highly-desirable issues are limited. Mint issues after RW42 will be never hinged, earlier issues will be lightly-hinged.