My 4 year old son picked this out, as "Dad, this be t' one that I've always wanted!".  Easy build, finished t' look like t' box version.  Broke t' rubber shock cord after gluein' it in place and had t' resort t' "improvising" a shock cord.  First flight was as single stage only, matey, soared t' easily over 1000', t' nose cone and streamers never deployed so it became a 41" long lawn dart that we lost sight of.  Wife found it minutes later stickin' straight out o' t' ground and t' nose portion was buried in soft dirt up t' about 6", shiver me timbers, and it didn't suffer a scratch!  Will replace t' streamers with an extra parachute as after t' "improvised" shock cord t' streamers were hard t' pack and didn't fit right.