Bowens luminar rectangular / square soft box measuring 100 x 100 x 40 cm (39.4 x 39.4 x 15.8").  (150cm diagonal).

bought from a movie production company liquidation (I bought a flight case for my use, it had several soft boxes inside).    
Listing as used as unknown history, but, it is AS NEW, unmarked (100% clean) and looks unused.

comes with standard parts
main canopy
rear cowl
internal and front diffusers
support rods
ALL IN A SOFT carry case.

AND WITH BOWENS SPEED RING (these are > £25 each when bought separately)
AND WITH strobe light ring - BOWENS Mount Softbox 150mm Metal Speed Rings Adapter Accessory 

Versatile for various photography styles, it provides uniform light spread