Our Wood Nesting Trays are 2-piece tunnel systems. Precision-machined of solid Northwest alder, these trays are designed to provide holes with the correct diameter and depth that female mason bees require to lay their eggs. The 2-part tunnel design makes harvesting the cocoons and cleaning simple no need for tube liners. The tray system features a side-locking design to seal out predators, and when assembled, the color and slightly uneven texture of the block face aids the bees in identifying their tunnels. Contains 7 trays with 48 holes and includes 2 heavy-duty rubber bands to ensure stability. Dimensions are 5 1/2 inches x 3 1/2 inches x 6 1/4 inches.