The Stirling engine base is made of mirror stainless steel, glass cylinder liners, precision bearings, bearing steel shafts, and zinc alloy flywheels. All parts are surface treated to avoid rust. Oil free. Easy Start: Just put a spin on a cup of hot water and you're ready to go; just maintain enough temperature difference. Wide range of applications: People buy it for kids science projects, physics/mechanics learning, classroom presentations, and more. Elegant design and fine workmanship, this is a beautiful . Colour: Gold Material: Metal Package Contents: 1 * Engine model Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.