Model rocket engines contain a flammable solid similar to black powder. They are considered to be hazardous materials by the Department of Transportation (DOT).

We cannot ship these items by air and ground shipments fall under a special DOT exemption. Packages containing any rocket engines, including some starter kits, are subject to a special HAZMAT fee of $12.00 or more. This makes rocket engines impractical for mail order shipment. We do carry rocket engines in our retail stores where the HAZMAT fees do not apply.

Note that rocket starter sets usually contain rocket engines.