These are not the E22 batch engines! The Estes C11-7 engine is an upper stage engine designed for model rocket flight. This engine can also be used as a single stage engine in lightweight rockets. Each package includes 2 engines, 2 starters and 4 starter plugs. Estes model rocketry is recommended for ages 10 and up with adult supervision for those under 12. Unless otherwise specified, all models require assembly. Tools, construction and finishing supplies sold separately. In order to launch, a launch system, model rocket engines, starters and recovery wadding are required - sold separately-unless otherwise specified.