Here are what I show for Cox engine clips, I dont have the Cox Little Joe II so can not speak with authority on it, but believe it uses the same 18mm clip as the others, also note on the Nike, the booster loads from the top, and the "ejection tunnel" is the retainer for the booster section, turned by the "key" included. Also the Saturn 1B has the option of single 24mm or dual 18mm.

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