From this page you can purchase a complete post kit including the vertical post and post arm.... of if your existing unit was damaged, you can purchase the replacement parts. In order to purchase replacement parts, you must be 100% certain that you own a Mayne Charleston Plus Post. These parts will not work with any other brand mailbox post.
Made from: Polyethylene
58'' H x 8.5'' W x 26'' D.
Available Color: White, Clay, Granite and Black
Warranty: 15 years
Mounting posts required: 4 x 4 (6' long)
Ships from factory warehouse
Delivery: 1-2 weeks
Mail boxes, mounting kits, or 4x4 post inserts are not included.