Heat Exchanger, Cold Finger, for 2-5L Bio Reactors. Heat exchangers are available in a choice of two different styles. The cold finger style is for use with 3 and 5 liter reactors and fits into the headplate via an M18 threaded port. The second style is a loop type exchanger and is available for 5 - 15 liter reactors. It fits into two, M10 ports of the headplate.Like-for-like replacement parts for Applikon Biotechnology and Broadley-James brands of bioreactors.Applikon is a registered trademark of Applikon Biotechnology, Inc. Broadley-James and Broadley-James Corporation are registered trademarks of Broadley-James Corporation.