Keep predators away from your backyard birds using the Woodlink Cedar Predator Guard, This cedar square may surround any bird house opening 1, 5"" or less in diameter to prevent entrance by predators such as blue jays crows grackles and opossums, This guard will not deter your birds from entering the bird house but inhibits entrance by larger birds and animals, This guard easily fits over bird house openings and may be attached using the two included screws, The Woodlink Cedar Predator Guard protects eggs fledglings and even adult birds from predators, Made in the USA, Construction: Cedar, Dimensions: 2-3/4"" L x 2-3/4"" D x 3/4"" H, SKU: WDLNK086