49.2mm String Spacing. Very nice quality. Fits most standard old '50s-'80s Gibson spaced humbuckers, Lindy Fralin Gibson spaced humbuckers and many other vintage Gibson spaced humbuckers exactly. This is an 'old school' cover for use on vintage humbuckers where the neck and bridge pickup have the same pole spacing. I measured 49.2mm/1.937" E to E centers. #GBNC