Fins are formed monolithically from the material of a tube body. The fins extend from the tube body outer surface, and include a fin base and a fin top. Wings extending from a fin side surface between the fin base and fin top can produce upper and lower channels between adjacent fins. Depressions can be formed in the fin top with platforms below the depressions. The tube can also include helical ridges on an inner surface of the tube. The tubes are used for heat transfer, and can be included in shell and tube heat exchangers.