The Lastolite Umbrella Box combines the features of an umbrella and softbox. It takes light from your strobe head or monolight, reflects it into its white panel, then softens it again with a diffuser on its way out.
Some older flash heads (Elinchrom, Profoto...) have very narrow (7 mm) umbrella receptors. This Umbrella Box model has a narrower-than-standard shaft to fit such a light.
This 41" size is perfect for one-two person head-to-waist shots, or up to a 5x7' product setup.