A string nut

[rounce55]

thanks guys i want a nut that will help prevent the guitar from getting out of tune

 

[dbw]

There is no competition here, it's graphite.  A roller nut might be good too but I've never tried one

 

[blue313]

IMO Graphtech.  Graphite is the "slipperiest" of the bunch and would have the least tendency to bind.  Although vintage bone isn't bad if the slots are polished out.

 

[tfarny]

1. locking
2. roller
3. graphite