ID: 
2300
Maker's Name: 
Unknown
Where made: 
China
Dimensions: 
10.3 × 10.3 × 12.8 cm

This is a closed cycle external heat engine. With a large displacer piston and small power cylinder/piston, this engine was designed to work with small temperature differences eg it will work when sitting on a hot cup of coffee or on a few ice cubes. The loss-free efficiency is a maximum possible 9% to 12% in these cases.