I fitted these to a small-bodied electro-acoustic, a Yamaha APX-4A. It was a bit awkward as there's very little room to manoeuvre one's hand inside the body, but after a bit of patience, and also some cramp (!) it wasn't too difficult - it would be very straightforward fitting them on a full size acoustic. It has made a noticeable difference to the sound; it really rings out. The bottom string didn't used to do much more than a thud, but now it sustains beautifully. Added to this, the ease of string changing (not having to hold down the peg with one hand), and the fact they look pretty sexy too, I highly recommend them. Thomann's service is excellent, as is the tracking service; I ordered them on a Thursday night, and they were with me Monday morning - from the warehouse to my door in less than one and a half working days! - Excellent!