Bought it as a replacement for the stock Roswell VTN-4 pickup in Harley Benton PB-50, not that it need it, but because I wanted to. Even if higher (5 mm) than stock pickup, it fitted without routing. Provided wiring kit replaced the stock pots.
I chose S4 because of humbucker rail construction and the advertised characteristics, favouring low & high ends.
It gave the PB-50 a smooth overall response, noiseless, with bright highs and well defined lows. It tends to distort at max volume.