Hi.
I have a couple and I love 'em.
Super easy to use, IMHO. I bought one for a guitar from my guitarist, he couldn't figure it out

. But the drummer did

.
They do break up really easy though, so be careful.
Allthough I have the equipment, I haven't measured the accuracy of the strobe (lazy me), but with my one good ear, close enough

.
Edit. HOLY CRAP, 33.99 Au$. That thingie comes "free" with double set of Daddario strings for approximately same in €.
Regards
Sam