From Manufacturer
The Lastolite Ezybox II Switch Large is a lightweight light-shaping tool that adds a flattering, low contrast quality of light to studio, battery-powered and shoe-mount flashes. The Switch neatly solves the problem of choosing between square and rectangular formats. With the Switch you have them both in one softbox. Measuring at the front diffuser you start with a 35 x 35" square - a good size for head and shoulder portraiture. A simple zipper narrows the Ezybox to 35 x 17" for use as an accent light or for reflective objects such as glassware.
The Ezybox Switch has removable interior and exterior diffusers that can be used in any combination or not at all depending on your subject and desired effect. With both inner baffle and front diffuser in use there is a 2.0 stop reduction in output. Please note that the Ezybox requires separate purchase of a speed ring for use.