Rainproof Design: Our through the wall key drop box features a safety rainproof design with a large shield placed in front of the delivery slot, ensuring the security of important mail even during heavy rainfall. The bottom of the box is equipped with rubber pads and drainage holes to quickly remove accumulated water, preventing mail from getting wet.Large Storage Box and Slot: The through the wall drop box includes a 12.5x6.3x16.9 inch storage box, providing a space of 0.74 cubic feet, capable of accommodating various items. The 1.6x9.8 inch (40x250mm) slot is suitable for smartphones, envelopes, and small packages.Durable Materials: Constructed from heavy-duty steel and coated with rust-resistant powder, the through the wall mail box is sturdy and durable, with a scratch-resistant surface to maintain its appearance. Equipped with a spacious visual window measuring 2x4 inch (50x100mm), allowing for easy viewing of mail without the need to open the box, providing you with instant access to your mail status.Combination Lock for Security: The use of a combination lock is convenient, eliminating the hassle of lost keys and allowing for password changes at any time. The interior of the mail drop box features metal baffles to prevent theft or fishing of important mail, making it suitable for use at home, in offices, workplaces, or schools.Easy Installation: Our through the wall locking key drop box is equipped with adjustable slides suitable for walls 2.8-7.9 inch (70-200mm) thick, compatible with various common wall types. The mailbox is designed for easy installation and comes with detailed installation instructions, making it easy even for beginners.