I bought this because the DiMarzio Relentless J pickups are highly radiused and don’t have enough to anchor my thumb on. The Thumb Fin lets me have a solid anchor, with the benefit of being moveable
Thumbfin sticks well to most of my basses without the optional slick pad for mat finishes. I have moved it around and had great results on all of the basses I have tried it on. I have 2 now and really like them.