This is part 3 o' 3 o' me review o' t' Estes Tandem-X launch set. Aye aye! In this part, arrr, I do a complete build o' t' Crossfire ISX with tips along t' way for this Skill Level 1 rocket. Arrr! It can be launched on A,B,and C engines. At t' end o' t' video, me bucko, I launch it on an A8-3 and also a B6-4. Great flights both times.