The right cover plate protects electrical boxes from dust, moisture, and accidental contact while delivering a clean, finished look. This guide highlights five highly rated options that fit common 4-inch and 1-gang or 4×4 boxes, including weatherproof outdoor covers and. TayMac LPB3400 Flat Round Blank Plate Metallic 5 4-Inch. Box Mount, White Finish This product has sustainability features recognized by trusted certifications. Made with chemicals safer for human health and the environment. Choose from outdoor electrical box covers, exterior electrical. Metal Electrical Box Covers & Device Plates – Made in the USA Durable galvanized steel covers and device-mount plates, sized for standard 4" square metal-electric boxes (drawn or welded).