I bought this kit for my dad with the 38mm motor. I think this combination leads to a very flexible second or third mid-high power rocket. There were a couple of problems with my order which were immediately and thoroughly corrected. The fins required a little fitting but it is better to have to sand the tabs down than to have them not reach the motor tube. The quality of the materials used in the kit and the customer service I experienced was top notch. The reason I would not suggest this as a first kit in moving past low power is that the directions leave something to be desired for a builder new to high power. If you have done a kit with through the wall fins, rail buttons, have solved motor retention on your own, etc, or if you have an experienced builder handy, there is nothing challenging about this build. This is really the only deficiency that I can find with this kit and is completely irrelevant to a builder with any experience. It is the sole reason that it did not get five stars.