Kolossos is the Greek word for a statue, much larger than the original subject. Seems fitting for an oversized derailleur cage with a 19 tooth bottom wheel.
Besides reduced friction, this cage is built with shifting accuracy and chain retention in mind. Kogel Bearings has always had a strong connection to off-road disciplines. We wouldn't build it if it weren't gravel proof.
Oversized pulley systems are an excellent way of reducing the additional friction caused by clutch derailleurs. Run it on a 1x or 2x setup, it is your prerogative.
This model is built for the GRX 2X (RD-RX810) and Ultegra RX800 series derailleurs. This includes mechanical and Di2.
This cage fits on the GRX 1x derailleur (RD-RX812) and will allow to shift through the entire range on an 11-42 cassette, but it will leave a large spacing between the top pulley and the smaller cogs. Expect shifting to be less snappy in these three gears in a 1x setup.