Finish similar to black epoxy. Hex size 3/4" (19mm). The overall diameter of the domed seat is 23mm. It is very odd that Dorman 711-305 Chrome Lug Nuts (same part number but in chrome) have a 13/16 inch (21mm) hex size and an overall lug seat diameter of 24mm. Unfortunately I had to send them back as my OEM Volvo rims have a 21mm bolt hole and the black versions of these lug nuts don't have enough clearance for my comfort.