A heat spreader includes a main body extending between a front and a rear configured to be mounted to a cage and heat transfer fingers cantilevered forward from the front of the main body. The heat transfer fingers each have a fixed end, a distal end, a top, a bottom and mating edges facing each other across gaps. The heat transfer fingers are configured to be received in corresponding channels between heat transfer fins of a pluggable module as the pluggable module is installed in the cage through the front end with the gaps receiving the heat transfer fins. The mating edges are configured to face and be thermally coupled to corresponding heat transfer fins. The heat transfer fingers transfer heat from the heat transfer fins rearward toward the distal ends and into the main body.