ORIGINAL: Ken Kehlet
Many "Foreign" model airplane engines are shipped without a Glow Plug and without the carburetor installed. The company that manufacturers the engine pays less Exportation Fees because the engine is not fully assembled.
The import company pays less Import Tax, because the engine is not assembled and is not yet a completed ready to run engine- (less the Glow Plug).
The "Glow Plug" was invented in USA in 1947 by Ray Arden. It caused the downfall of Small Spark Ignition Model Airplane Engines.
The Universal Glow Plug THREAD SIZE that is available here in USA is 1/4 X 28.
Some countries, Brazil for example, charge as much as 300% Import Duty on Model Airplane engines unless the package is marked as a GIFT, Unassembled, and the Value is marked at much less than the engine is worth. In some countries, the Customs Office has been known for holding Items until a "Liberation" price is agreed upon.
Here in the USA, our commercially made Glow Fuels contain from 5%-50% Nitro Methane. Most other countries use FAI Fuel, or "0%" Nitro in their Glow engines because Nitro Methane is very expensive or not available at all.
Glow engines running "0%" Nitro require different head shims and spacers to run properly on 0% Nitro Fuel. Maybe a different heat range of Glow Plug also.
The LEO Engine is a good Sport Engine. About the same quality and durability as a MAGNU ASP, BRAT, Thunder Tiger, or Bluebird. Maybe not as good as a O.S. Engine, but the price is well below the cost of aO.S. engine.