Updated: May 26, 2019
If changing the seat on a Bonneville T100/120, Street Twin, Street Scrambler or Street Cup it will effect the type of fender eliminator set up.
1/ Stock Bonneville seats have a deeper rim around seat which requires a lower mounting FEK bracket. (Top two pictures)
2/ Street Scrambler /Street Twin seats have a shallower rim that just cover sub frame tubes.
3/ Street Cup seat has no rim and exposes the sub frame tubes. (bottom two pictures)
So if you are changing a stock seat for a bench or cafe seat that exposes sub frame tubes, consider a Street Scrambler or Street cup FEK depending on height seat sits on frame.
Keep in mind, fender eliminator kits are categorized by name to fit with stock seat.