Low temperature Stirling, steel

Low temperature difference stirling, polished high-grade steelThese Stirling Engines will run on any warm surface (i.e. a cup of coffee, TV, computer monitor, a human hand, etc.). They simply require a small difference in temperatures. They works both ways, so they'll run backwards when placed on a cold surface (i.e. snow or ice).These engines are a great gift for any person, who likes technology or physics. Also, they are an interesting decorative item, which certainly attracts a lot of attention. The engine demonstrates several scientific facts and phenomena which makes it a wonderful educational item for physics, engineering and thermodynamics in particular. It comes with a brief description of Robert Stirling's invention and some helpful operating instructions.Dimenstions are: 3.5" in diameter and 4.9" in height. All parts are precision machined brass and aluminium and mirror-like polished stainless steel. Each engine is assembled and tested by hand in Germany.Highest quality low friction and lubrication-free ball bearings are used.Each cylinder / piston combination is an individual match machined to micron precision with a special low friction surface treatment.Airtight seals are O-rings (on acrylic glass) and aerospace grade resin (on brass cylinders).There is hardly any wear on these engines. If operated within limits, they'll virtually last forever.Balanced flywheel to compensate piston weights.Recessed screw heads for a perfect heat flow to or from any flat surface.The model made from polished stainless steel outlines the "all metal" appearance of the engine.Due to the higher strength of steel opposed to aluminium a thinner gauge of material was selected. Therefore the ability to conduct heat remains just as good as with our anodized aluminium model although this material reflects some radiation and aluminium is a better heat conductor.