As an engineer, I have been involved in aerospace and commercial Stirling technology for many years, and have recently purchased several units similar to this one from Stirlingkit for an educational demonstration. This is one of my favorites. The workmanship is excellent, the design is surprisingly (for a "toy") refined, and it is sturdy and reliable. 10 thumbs up!
This thing is awesome! Impresses all that inquire about what it does, and nobody expects the rpm's this thing puts out. I bought this for what I call "Man Candy" which basically means the stuff we dont need, but have to have. I will be purchasing others from this seller (non-bias review), just happy with the product/shipping/service. If you're thinking about buying it, do so.
This is a very elegant and smoothly functioning model Stirling engine.