These are new framesets that had been assembled into complete bikes at the factory. Alloy frame, carbon fork. Compatible with a chain or belt, and with conventional drivetrains, internally geared hubs, or single speed. (Note that if you use a belt, your gearing options are limited to either single speed or an internally geared hub.)
The bottom bracket is eccentric, but belt tension is independent of that, so you don't need to mess with the bb when you change a tube or tire or when you reinstall the rear wheel for whatever reason.