A popular size especially in the garden, SM-32 models are built to a scale of 16mm/foot and run on a gauge of 32mm, the equivalent of a two foot gauge railway. SM-32 has become the first choice for many narrow gauge enthusiasts who want to operate live steam locomotives by radio control, the large size of the locomotives means plenty of room for the receiver and control servos. The ST-607 is designed to match the small radius turnouts SL-E691 and 692, making it easy to construct parallel sidings and passing loops, and to provide an outer (Second Radius) circuit to the ST-605. The SM-32 Setrack system is also compatible with the SM-32 Streamline track system.