Tony, the Poundstretcher one seems to be the latest design. I saw a similar one yesterday, about half the size of my original one, and still with only two nozzles. The triple one looks even more like rocket engines. I did consider getting one to make some sort of 1 man interceptor, but did't really have the energy for it at the moment.
The fin on the top is from a TMNT space cruiser toy. I only just bought it, and realised the fin was the last thing I needed to finish my rocket. The surf fins are flat on one side, so would look wrong as a dorsal fin.