All steel, gloss black. Parts numbers with two patterns listed are dual bolt pattern wheels. Inside nubs for 17" & 18" caps is 7"; all other sizes measure 7 1/2". A cap is included with all wheel sizes. C52 cap is the only cap that fits 20". NOTE: 14"-18" options have a ring around the hubcap area, 20" & 22" options do not. See Series 513 for picture of 20" & 22" center detail. Doesn't fit Jeep Samurai. Lug nuts not included. Please check fitment before mounting.