The Small Pro Plus Strip Softbox is designed for use with a strobe. With fabric not intended for the heat of a continuous light, the Small Plus Strip comes standard with a silver interior and a recessed, removable front face, which provides more control of light than a box with a flush front.
The "plus" designation means the front face may be removed. A 1/2 or 1/4 strength fabric could be used instead, for slightly more light transmission and less of a softening effect.