What you'd use it for
Four Rainbow 2 tubes in a case, which is the sensible way to buy them if you are running more than one. The multi-pixel RGBX colour system means each tube can hold a flat colour or split into pixels for gradients and chases, and four of them cover most of what a small unit needs: a soft key, an edge, a background wash and a spare. The case is what makes it travel.
Length sets the fixtures in the case: four 2ft tubes at 25 W each, or four 4ft tubes at 50 W each.
Figures published by Quasar Science.