I would like to get a medium size portable softbox which I can use with my Canon flash and profoto strobe.

I have looked around. I like Photoflex Litedome and Wescott Apollo 28 a lot but the problem is that they only work with camera flashes but not with powerful strobes. At least that's what BH says on its website: "for camera flash only".

Do you know any softbox/octabox on which I can set up my camera flash and a profoto speed ring as well?