This is a Matthews 20 x 20 ft sewn Hi Lights Mylar Butterfly/Overhead, to fit any Matthews, or other brand or make frame. 20 x 20' Butterflies measure approximately 19.8 x 19.8 ft.
Matthews fabrics are tested for even light distribution in a black chamber with an incandescent light source at one end and the fabric positioned 2/3 of the way between the source and the digital light meter.
For minimal softening of sunlight, or studio fixture output. It has a density similar to a shower curtain.