The Lightsock 20 is a covered wagon style diffusion system made specifically for the Astera Helios. When used without the included blackout and you can reduce the aperture to 180°. Add the second to reduce the aperture even further. Access the back of your Helios through the provided cutouts with your fingers or clamp of choice. Use the M5 threaded holes on the knurled aluminum ends to attach your Astera floor stand.