Baldwin Magazine Size Mailplates. Spring Tension Design, Weatherproof. Made of heavy gauge wrought brass. Overall: 10" x 3". Inside Opening: 8.25" x 2.375". Specially designed for use on exposed doors to prevent wind from driving rain and snow through the slot. Bronze spring keeps flap tightly shut & permits vertical installation. A sleeve (0050-324) is available for hollow core doors. Oil Rubbed Bronze finish.