I bought a couple of these, in order to replace some of the cheap plastic ones, I had on some of my guitars. Bone really does make a difference, in tone and harmonics, when it comes to replacing the nut.

Overall I've found these nuts to be decent, but it's not without flaws..
Some of them have their string slots cut inaccurately, and a little off the general string spacing.. It may vary from nut to nut, but I had one like that - where as the second one was alright.. Might just have been that one - anyway.

Pre-slotted bone nuts will always need some adjustments, sanding and fitting - that's just the way it is. Really, it's no big problem, just use some fine grits of sandpaper and it'll all be fine.