Two lug (F5000) plated steel with dry film lubricant applied. Counterbore in base area of nut eliminates shimming to prevent bottoming on the imperfect thread. Use to allow engagement of thread in cases of bolt hole misalignment. Attach with 3/32″ diameter rivet, except L6 uses 1/8″ rivet. K designates countersunk or dimpled rivet hole and L designates dry film lubricated (black).