SPECIFICATION: 7 spline socket key – ID:0.78″ (20 mm), OD:0.9″ (23 mm), Overtall:3.5” (89 mm), Works with lug nuts wrench: 13/16′ (21 mm) & 7/8′ (22 mm). Black coating can greatly improve rust and corrosion resistance, preventing the outer layer from peeling off.