I have sold many of these rubber shrouds in the past. They are typically stamped with the patent date but usually this gets mistaken as the production date. What most collectors are getting are newer thicker masks. This mask is actually an early production mask from the 70's. You can tell because the casting is thinner and the color of the rubber is pinker and has a distinct rubber feel. This particular mask has two places where stabilized nicks are present--most noticeable behind the ear. This was not because of misuse but rather the thin early casting. A very nice early shroud for those in the know.