The inner tube is made from 12' of 5/8" convoluted (twisted) copper which continually turbulates the wort as it flows through. The outer tube is made from 7/8" copper. The Convolutus chiller allows you to pump wort through without having to restrict your pump to slow down flow. Use 1/2" line to connect to wort in and out feeds. The water connections are male and female 3/4" hose connections. 10 1/4" height by 11" overall diameter (coils themselves are about 6" in diameter).