Nothing to do with squirrels; this post is intended to help you make the correct choice when replacing your guitar’s nut. If you like to play play a tremelo arm or whammy bar as part of your style but find that your strings just keep breaking then this post will hopefully get you through! Even if you don’t whammy like a madman and your strings continue breaking at or near the nut then it’s time to consider a replacement. You may also like to consider upgrading the saddles in your bridge if you find consistent string breakage a problem in this area also.
The nut is the part of the guitar at the end of the fretboard which the strings pass across where the headstock and fingerboard meet. The nut is ordinarily a small strip of bone, plastic, brass, corian, graphite and stainless steel with grooves for the string to sit within and some come replete with rollers and ballbearings to reduce friction.