The Estes A3-4T engine is single stage rocket engine. This engine is a mini engine designed for flights in lightweight rockets. Each package includes 4 engines, 4 igniters and 4 igniter plugs.
How does a model rocket engine work?
When the engine is ignited, it produces thrust and boosts the rocket into the sky:
After the propellant is used up, a delay is activated, producing tracking smoke and allowing the rocket to coast:
After the delay is burnt, the ejection charge activates, deploying the recovers system: