Nitro skins feature individual parts which have been spray-painted with either black or tangerine orange colors and then reassembled. Currently, the Nitro skins family has only five members, all of which were added to CS:GO during different updates at different points in time.
Three out of five members of this family can be acquired as souvenirs which is why some members of the Nitro family can be worth around two thousand dollars. However, a majority of them can be obtained for a price of a few dollars or less.
Check out other CS:GO skins families: