I'm not sure, it appeared to be stock shape with a smooth marine vinyl cover but the foam was hard, peaked in the middle and sloped toward the tank. When I got on I had to drop my drawers a little due to the bunching up as I slid forward. The result of the peaked seat was my weight was concentrated on one spot. The result was I almost sang soprano after 15 hours on it. It made the rest of the trip not as fun as it could have been.
The hacksaw blade foam trim job I did after arriving made it a lot better, going home my legs supported some weight and no more sliding forward. Great bike after that. The PO of the 78 put on a big old cushy seat and wore it out while the stocker was stored away. I put the stocker back on and like it a lot.