I prefer these over A10s because they make for nice, slow lift-offs. These are very economical (4 per pack). We use them quite a bit to launch a mini Honest John and mini Der Red Max in our local park. I've never experienced a failure with more than 20+ launches.

Great all-around mini-engine. A good combination of power and versatility.

Have been using these A3-4T 'Mini' series rocket motors, for decades without any complaints, for small, light weight rockets. Wish Estes would bring back the Upper Stage release for this impulse class rocket motor A3-6T, it doesn't seem logical, now that it's discontinued. 'Mini' Booster, 'Mini' Single Stage, but no real 'Mini' Upper Stage, with a long delay, that way mini rockets can reach apogee without damaging their recovery systems.