Compensated nut. They do make you in tune. Test... hit open D then B string third fret. Are you close? Do you want as close to perfect as you can get? Questions? :
Compensated Nuts | TalkBass.com
Mastering the art of making the perfect nut for a guitar
Stephen Delft's Compensated Nut
What is a Compensated Guitar Nut? - YouTube
AlwaysHandCrafted COMPENSATED BRASS NUT made for FENDER / SQUIER Guitar - 42mm | eBay
Sound Offset Spacer Compensated Guitar Nut S.O.S for Electric Guitar MTS Theory | eBay
Replacement Ernie Ball Music Man Compensated Nut 1-5/8 Black | DuBaldo Music Center
S.O.S. Nut Compensation | goeldo music - Wholesale guitar parts, tools and accessories.
Nut compensation - FRETS.NET
compensated nut for electric | The Canadian Guitar Forum