Crabgrass Plus Crabgrass & Lawn Weed Killer, 5,000 Sq. Ft. Coverage Horse Health Products Durable rust free galvanized wire meshPredator 1 4 soft wire Durable rust free galvanized wire meshPredator guard extends entrance hole to protect against predatorsPredator guard entry hole has a diameter of 1 1 2" Predator guard with an entry hole 1 9 16" in diameter for Western bluebirds can be purchased separately on the Replacement Parts page and retrofit to the bluebird houseBluebird house body has an entry hole with a diameter of 1 9 16" to allow it to be used for both types of bluebirdsFledgling kerfs provide extra grip for fledglings to climb out Accurate and simple to use 4 d to kill many kinds of lawn weeds including hard to control mature crabgrass without harming lawn grasses for home lawn use