Low Temperature Stirling Engine by CTU BroHall Item Name: Stirling Engine . Size: 102 X 102 X 125mm . Material: Steel and Glass . Speed: up to 180-250 RPM . Start Temerature Difference: 20 ? . Weight: 250g . Features: This Low Temperature Stiring Engine could be a great gift for your friends or families. . It is almost ready to run: after the installation, put it on a cup of hot water, then it will run itself. . Note: Can use pencil to lubricate all the connections,other oils are not recommended. . Package Included: 1 x Low Temperature Stirling Engine