I bought a couple of these to accomodate different types of string. The original nut is quite soft and weak- these seem better and I won't get stuck in limbo if I file too much off. I am now on Daddorio Flatwound Chromes - I just had to enlarge the top two grooves slightly, then reduce the overall height of the nut a mm or so to get a really low action. At the price they are well worth buying as spares.