I have several bikes which have both an under seat tool bag, and a Seatpost mounted mudguard. The mudguard blocks any rear light mounted on the Seatpost. The knog seat mount, is wide enough to mount the rear knog light, under the seat and behind the tool bag, such that it doesn’t stick out behind the seat.
The design itself is clever and works pretty good. But the choice of materials seems to be wrong. I lost my wonderful and expensive KNOG rear light with this mount :-(
Love it 🥰