4" Round Screened Vent - tab style, black - bag of 4 No Screen vents - tab style They fit into the hole

They fit into the hole made by a drill-type hole saw and are held in place by knobs on the side of the vent

846si nfa (square inches of net free ventilation area)

plastic or glass

They do not have screens

4" Round Screened Vent - tab style, black - bag of 4 No Screen vents - tab style They fit into the hole4" Round Black Screened Vent, tab style bag of 4 RBLT 100 4" 4PK These round aluminum vents have louvers and a screen to keep insects out. They are easy to install. They fit into the hole made by a drill type hole saw and are held in place by 4 tabs on the side of the vent. No nails or screws are needed. Note: These are made for thin materials like metal, glass or plastic. They do not work well in wood. The tabs need to be bent over from the rear.