Just got my spanking new StrobeGeek bag. I tried and it does fit a quadra or even two I think. In the image seen above I stuffed it with a canon 430exII, set to fire on full power and a gridded 21cm Quadra to light up the logo on the bag. I fired the flashes with my skyport tiggers.
Next Time I will Try with some smoke as well. It would be cool to get a shaft of light coming out of the bag, don’t you think?