light screens that block light but let air pass?

is there anything like this i could put in front of my vents so no lights get out but air passes in?

light wont bend but does reflect so a couple duct elbows paints black on the inside will do what you need

i usually just get some cardboard and line it with either black tape or paint the cardboard black what will be on the inside then do a square and 3 pieces of black cardboard inside- (the top view)- so the air still gets through but no light does. found it on the web a while ago but cant remember the exact website

i drilled 4 inch holes and bought darkroom louvers from midgetlouvre. Just be aware that if a normal 4 in hole is enough venting without any obstruction than you need at least 3 to account for the same airflow.

good to know thanks..