Wort Chiller counterflow
This Counterflow copper wort chiller is a very good conductor of heat.
These units are 23cm in diameter and about 18cm high. The input and output are approximately 10mm outside diameter. These can be used with gravity but are recommended to use with a pump.
They are similarly efficient as the 30 plate chillers however they are easier to clean as they do not have all the small crevasses to trap hop material and other solids.