Grill with a flange and (4) screws to hold it in the foundation opening, has no flap or slide mechanism to open or close it, so the air can constantly move through. SKU: 42905917 MFG: 510BL Shop more products by Bestvents. SHARE Share on Facebook Tweet on Twitter Share on Google+ Pin on Pinterest Free shipping over $35 $11.78 Quantity In Stock Add to cart Request a Bulk Quote Thank you for your quote request. We will be in touch. DETAILS Description DESCRIPTION Highlights: Material: Polypropylene Finish: Black Oxide Depth: 7-3/4 inch Height: 8.5 inch Rough Opening Size: 8 in L x 16 in W Suitable for: Standard Block Foundation Opening Width: 15-1/4 inch FEATURES MFR: 510BL SKU: 42905917 UPC: 008661510012 Brand: Bestvents