The 900-3520 Astra 1x1 Adapter frame is designed to accept barndoors and honeycomb grids from the original 1x1 so users can shape the Astra's light output and help from unwanted spill. Use the Adapter frame on any of the Astras to be able to be used in conjunction with Barndoors and any of the Honeycomb grids (30°, 45°, 60° & 90°).