That is the second release of the Mongoose? The orignial mongoose was the rerelease of the Estes scorpion, which was my first multistage rocket. The stage assembly is a little different between the Scorpion and the moongoose, where the booster body tube has no protection between the top centering ring and the "support ring" on the inside top edge. For my second mongoose I built I extended the booster motor tube the whole length, and had a centering ring flush with the top of the booster tube. Next one I will build, I will probabily use a tube coupler if possible.