In order to stay compact and lightweight, most folding bikes have just a single chainring, limiting their hillclimbing capabilities. The Easy Ride is made to address that issue, by incorporating two shiftable gears into a custom single-ring crankset.
The shifting mechanism looks similar to the Buffalo Utility S2 from World Bicycle Relief. But the Buffalo uses two chains for the two speeds. Contavelo say they use a gearbox inside the crankset. I’d enjoy a more detailed explanation - the best I found were these graphics:
Exploded view:
Low gear:
High gear?:
That bike is pretty cool, I like their mission too.