A heat exchanger assembly (10) for transferring heat comprising a plurality of hollow tubes (12) and a bridge (14) integrally interconnecting adjacent tubes (12). The plurality of tubes (12) are interconnected by bridges (14) forming a heat exchanger core. Each bridge (14) includes holes (16) extending through the bridge (14) to allow airflow through the holes (16). A method for making the heat exchanger assembly (10) comprises the steps of simultaneously extruding hollow tubes (12) and bridges (14) integrally connecting adjacent tubes (12) through a die; and cutting holes (16) into the bridges (14) to allow airflow through the holes (16). The holes (16) are cut into the bridges (14) by cutting tongues (18, 188) into the bridges (14) and bending the tongues (18, 188) transversely to the tubes (12). Fin modules (20) may be inserted into each hole between the hollow tubes (12) to provide alternative heat exchange characteristics to those of the tongues (20) acting as the fins.