Gibraltar GMB225BAM Mailbox Mounting Board, Polymer .15 Ga. 17" L Black Durable construction Fits standard No. 1 mailbox Fits vertical or cross arm post Polymer will not rust or rot Developed specifically for use with all sizes of Gibraltar Patriot mailboxes and plastic posts, the Patriot mounting board snaps easily onto the bottom of the mailbox so it can be installed quickly and easily to the post without the need for any hardware. The mounting board is also compatible with 4x4 wooden posts and can be screwed in directly with additional hardware. Made from polypropylene plastic that offers outstanding strength and stability, it's treated with an ultraviolet inhibitor to provide long-term service. Mount Type Top Mount Each Weight 0.900 LB Material Polymer Product Type Mailbox Mounting Board Gauge .15 Ga. Length 17" Width 6-1/2" Color Black Hardware Included Yes Screws Included No Alternative UPC 071691727910, 793503122514 Depth 3.6 In. Mounting Screws Included No Width 6.4 In.