I’m not familiar with your particular application, but our Fantastic Fan vent doesn’t have a shade, just a screen. For room darkening, Arctic Fox supplied a square faux leather cover that attaches with snaps at each corner. To help seal out the light better I added velcro between the snaps and foil insulation to keep the heat/cold out. Not as handy as a sliding blind, but it blocks out the light (better?) and is easy to remove when you want to use the vent. Best of all there are no moving parts and would be simple and retalitively cheap to replace.