The 18" x 8" x 5" Williamette Graystone Foundation Vent Well Block is designed to securely enclose and protect foundation vent wells. Made from durable, weather resistant materials, this block helps prevent debris, dirt, and pests from entering the vent while still allowing for proper airflow and ventilation. It acts as a barrier against water, preventing moisture accumulation that can lead to mold, mildew, and foundation damage.