Designed to be versatile, sturdy, and easy to use, this bottom board is stand alone. It needs no other bottom boards or add-ons to function. A 1/8” mesh screen covers the entire floor allowing for greatest ventilation and mite drop possible. 3/4” strips around three sides provide the entrance. A white vinyl-coated masonite tray slips in the back (or front if you specify) on a track below the screen to monitor mite drop. By using 1 3/8” stock for two interlocking frames we have achieved a very strong, durable construction. We recommend purchasing the assembled units because of the many pieces that make assembly difficult.