Fitted these to a Yamaha SG700s that I felt wasn't really holding tune very well. Easy to fit, though needed new pilot holes drilling for the screws on the reverse side of the headstock. Easy enough, take your time!
So far, so good. Guitar is staying in tune better. You need to remember to either carry a flat head screwdriver around in your case or gigbag to unlock the locking mechanism for string changing - or make sure you have a small coin in your pocket.... or even steal the mentioned small coin from your drummer, he'll never notice ;0)
Overall, very pleased with these, they work and look right on the guitar