Mainframe and cylinder are bronze. Boiler made of silver-soldered brass & copper with mahogany lagging. Boiler includes pressure-relief valve. Brass piston, connecting rod, and flywheel. Stainless steel driveshaft, crankpin, and springs. Runs on sterno - typically for 30 minutes. Overall- Length: 5" Width: 3" Height: 7½" Mainframe- Bore: 9/32" Stroke: ½"
See my ad for Midwest Harbor Tug Model Kit 956.