Lytron model # 4121G4 heat exchangers, new / surplus. These heat exchangers have an all stainless steel fluid path, with copper cooling fins for maximal heat transfer. Units come with two 24VDC fans attached. With the fans, the dimensions are approximately 6"x12"x3". Tube outer diameter is 3/8". To view a full specification sheet (PDF, ~800KB), click here. These units appear identical to the 4120 model but with inlet and outlet tubes shaped differently. We also have discounted units available here.