I bought these to replace the existing springs in my Strandberg as I was overhauling the tremolo system by installing a brass block and claw and figured I might as well put in some top quality springs while I'm messing around in there.
Compared to the existing springs, it's difficult to say how much difference there realistically is, but they're made in Japan so the quality is assured and I'm quite happy to have installed them and to not have to worry about replacing them in future.