Did you read the description?

This is the handbuilt mould from which mountain bikes came. Joe and some of the others... like Gary Fisher... were mountain bike pioneers in the 1970s and were the first to conceive of the purpose built mountain bike. This is from a very small pool of the earliest frames. There are lots of De Rosa's out there, not many of these. That means demand is much higher for one of these especially in this museum quality condition.