Built by Fairbanks-Morse between the late 1940s and the 1950s, the H15-44 and H16-44 locomotives were designed for road freight and commuter service. The units come in several carbody and cab variations including the early Loewy-designed version with rounded features such as the headlight casing and window frames, and the late body with squared-off cab windows, plus AAR Type B or FM truck sideframes as appropriate for each roadname. Other features include a smooth-running mechanism, realistic diecast chassis, directional red and green LED marker lamps (which work on both analog and DCC layouts); applied details including coupler cut levers, trainline hoses and scale winsdhield wipers, and painted crew figures in the cab. As Atlas Master locomotives, these new units come factory-equipped with an Atlas 4-Function, Dual-Mode DCC decoder installed. Dual-mode decoders allow operation on either DCC or conventional DC layouts with no difference in performance.