I have never had any Estes Rocket Engines fail me. They have a lot of punch, get-up, and go Just keep them dry and out of high humidity air for long periods of time. They will absorb moisture and when you use them they will ignite (maybe get your rocket off the launch pad) and then blow up including your rocket It's best to keep them in their package until you are ready to use them or if you have some loose ones put them in a zip-lock bag and keep them out of the Sun. The Sun creates moisture inside plastic zip-lock bags.

Want to send your low power 2-stage rocket out of sight? - These pack the expected Estes C power with zero delay to get your second stage lit right away.

Estes makes a good rocket motor. No problems at all with these motors.