Eccentrical chainrings.
WHAT ARE ECCENTRIC Chainrings?
Still retaining the standard round shape but after research and experimenting the chain ring is mount off center from the axle
ECCENTRIC-Geometry. not having the same center; not concentric
Reportedly able to save up to 70watts less in pedal power.
Eccentrical shaped chain ring by Controltec, CNC machined from 6061 grade alloy 53/41 combo designed to run on Shimano 4arm110bcd.
combo pack of 53/41
Checkout the online specs
https://www.youtube.com/watch?v=J9MlxOifuNY