The nut is great as any other Graph Tech product: good material, enhances the tone and stabilizes the tuning, but it will require some extremely accurate work to fit a P bass.
The length and the string spacing are correct, but it's very much higher and deeper than a normal P bass nut, so it will need a lot of sanding.
However, the major letdown is that it's flat-bottomed, unlike a standard Fender nut, and that complicates the installation a lot.
So my advice is: buy it if you're going to install it behind the fretboard, skip it if it's for a Fender-type bass 'cause installing it will be too much of a hassle and if you're not VERY careful you'll ruin the nut and need to buy another one.