Aluminum Sign Base By SmartSign | 14&rdquo; Od Stand With Sign Bolts & Nuts DURABLE. Sign base is made of aluminum and weighs 5.5 lbs. Sign base can be used indoors or outdoors. It is recommended to be used indoors, unless base is bolted to the ground. INSTALLATION. 14.5" diameter aluminum base includes hardware for attaching the sign post, and 3 pre-drilled holes for bolting the base into the ground. The U-channel post and the gag bolts (to attach the post to the ground), however, are not included. COMPATIBLE. Sign base is compatible with 6' heavy-duty or municipal posts. Signs measuring 12" x 18" are recommended for use on the base.