ELG stands for 'Enhanced Longitudinal Grind'.At the heart of this kit stands the longitudinally-ground trigger, which is ground in-line with the direction of pull along the long axis of the trigger, and then finish-polished. This grind and polish provide two significant advantages over standard mil-spec kits. First, a smoother pull with reduced grittiness and second, an enhanced basis for performing a trigger job.
Big Book Catalog, Issue:70, Page:038
Big Book Catalog, Issue:71, Page:042
Big Book Catalog, Issue:72, Page:047
Big Book Catalog, Issue:73, Page:052