For optical parallel fibre modules (PFM), efficient cooling is vital in order to fulfil reliability and performance requirements. The environment where these devices are to be used typically exhibits a wide variation in temperature, airflow and available space. Using optional external heat sinks attached on this device is a simple method to achieve a satisfactory cooling from a thermal and fabrication point of view. A selection of external heat sinks with cooling elements consisting of pins, flanges and foils have been evaluated experimentally on this device for varying air velocity (0-5 m/s). The thermal conductance of the device with attached external heat sinks is found depend essentially only on the thermal conductance of the bare module and the airflow exposed heat sink area. In addition, the attachment of heat sinks using adhesive films and the internal thermal properties of this type of devices are discussed.