The Tennessee Central Service Company nails were precursors to the steel nails from 1931 to 1941 with the trefoil or cloverleaf brass which was the symbol for City Service Group.Both East Tennessee Light and Power and Tennessee Eastern Electric Company used the steel nails from 1931 to 1941. City Service is best known for gas stations, but it owned both Tennessee Eastern Electric Company and Tennessee Central Service Company. In 1928 TCSCO changed its name to East Tennessee Light & Power. TEECO remained the power generation side of the company while East Tennessee was the distribution side. They eventually merged before the TVA purchase East Tennessee and sold it back to the local towns. You could once find these hubbards in Johnson City, Greeneville, and Bristol, Tennessee. Wesley Cole