Product Description Salsbury 3600 Series 4B+ Horizontal Mailboxes - Rear Loading - U.S.P.S. Access are ideal for apartments, condominiums, commercial buildings and residential developments. Manufactured by Salsbury Industries to USPS-STD-4B+ Specifications. 4B+ horizontal mailboxes are U.S.P.S. approved for replacement and/or retrofit installations. Feature a durable powder coated finish available in aluminum, bronze, gold and sandstone. Available in "A" size doors (6-1/2" W x 5-1/4" H) and larger "B" size doors (13" W x 5-1/4" H). Units with standard "A" size doors are available in 3, 4 or 5 doors wide and 5, 6 or 7 doors high. Units with larger "B" size doors are available in 2 doors wide and 5, 6 or 7 doors high. Salsbury Industries is an ISO 9001: 2008 certified company and has excelled in the field of manufacturing since 1936. From the Manufacturer Salsbury 3600 Series 4B+ Horizontal Mailboxes - Rear Loading - U.S.P.S. Access are ideal for apartments, condominiums, commercial buildings and residential developments. Manufactured by Salsbury Industries to USPS-STD-4B+ Specifications. 4B+ horizontal mailboxes are U.S.P.S. approved for replacement and/or retrofit installations. Feature a durable powder coated finish available in aluminum, bronze, gold and sandstone. Available in "A" size doors (6-1/2" W x 5-1/4" H) and larger "B" size doors (13" W x 5-1/4" H). Units with standard "A" size doors are available in 3, 4 or 5 doors wide and 5, 6 or 7 doors high. Units with larger "B" size doors are available in 2 doors wide and 5, 6 or 7 doors high. Salsbury Industries is an ISO 9001: 2008 certified company and has excelled in the field of manufacturing since 1936.