Those are a welcome addition. For 18mm RMS, I’ve been using Rocketarium aluminum motor retainers, which are a perfect fit. But a bit pricey. I bought a bunch when they first came out, and were on sale. The Estes 18mm retainers will be a nice, reasonably priced alternative on rockets I’d typically fly on Estes motors.

Thanks, John.

I weighed a couple of current Estes standard motor hooks and they’re 0.05 ounces....so not a big mass hit to use the new retainers. Sounds good to me!