I've written off GruvGear since trying the Fump and Fretwraps. They seem to produce inadequate solutions to problems that don't need solving with extensive marketing and then charge too much for their products
The Fump didn't work for me at all, but I usually put a Fret Wrap on most of my basses. No complaints about the Fret Wraps except I can't leave them laying anywhere or the cats get them. Fret Wraps are like $10. If I'm getting ripped off, it's not much.