1. The working model of the twin-spool turbofan engine 2. Full function electric 3. The engine starts with vivid sound 4. Independent low-pressure and high-pressure turbine structure 5. Lighting Effect Number of batteries: three 5th batteries (drive) Technical level: need to have a certain amount of hands-on ability, small age allows parents to assemble together, experience the fun of assembly together Colour:Photo Color Material:plastic Package Contents: 1 x DIY STEM Jet Aircraft Engine Model Kit Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.