... finned tube,3.7 times than smooth tube 2.Small flow rate, big temp. difference, 3.Best choice for heat ... steel ,thickness:4mm. Features:1)Thanks to the small flow rate, big temperature difference design,easy to get the high ... tube is screw thread,so the water will eddy flow forward ,it's another cause of high efficiency.3 ... is no block on water loop and the water flow is smooth,thus keep it avoid dirty.4) ...