Grover 505C Guitar Tuner

I would recommend this product to everyone

The current Grover tuners are relatively expensive but they are perhaps the best I have found and are backed by a lifetime guarantee.

Happy n satisfied with it

If you have a 12 string, these are absolutely necessary if you ever intend to change your strings. Two sets are required, and you will probably have to drill new pilot holes for the screws (I did have to on a Martin 12 but not on a Guild 12). That will leave the old screw holes, but I don't mind that slight cosmetic flaw. I've put the full sized ones on most of my guitars, except for the ones with Waverly tuners, and the minis are perfect for 12 strings. Easy to install and perform flawlessly with regard to accuracy and holding tune, as you'd expect from Grover tuners.Some practical advice: Saddles often aren't (and never should be) glued in, so if you remove all the strings the saddle will fall out. If you have an under-saddle transducer, it could also fall out and get damaged. I removed the lowest four strings and highest four strings, replaced the three lowest and three highest machines, and strung those up. Then I replaced the other machines and finished stringing. That way there was always some string tension on the saddle to keep it in place. Unlike another reviewer, I would never recommend (nor does Martin) medium gauge strings. The string tension of a 12 is such that you'd risk producing belly bulge, bowing the neck, or in a worst case pulling out the bridge. This kind of damage probably wouldn't show up in a month or a year, but it almost certainly would over the life of the guitar.A note of warning which really doesn't apply to 12 strings, as they take light gauge strings: The full-sized Roto-grip doesn't work on the low E (0.056) of a medium gauge set. It won't clamp down on the string. I thought it was a defective machine, so I contacted Grover and they promptly replaced it (Grover has outstanding customer service), but the new one had the same problem. I put a regular Rotomatic on that string, which is essentially cosmetically identical, and I don't mind tying off one string of a 6 string set.

I bought these since I don't want to pierce my fingertips when changing strings ever again. They fit my old (70s) Epiphone flat-top (10mm). I used an awl to start the holes I needed for the screws (I have screw holes visible now--bummer). Nice tuners, attractive, functional. Good-looking, unlike the Ratios I put on my Variax a couple of weeks ago--but those fit perfectly in the screw holes without the need to use the invisiomatch adapters.