Family Metal Word Sign Color:Hammered Silver True 4x4 and 4x6 post

True 4x4 and 4x6 post caps is 5" (H) x 3" (W)

Grapevine Wrought Iron Mailbox Post Accessory Dress Up Kit for Wood Posts

But enough about the toughness of this shelf

if the plastic post has really square edges these probably will not work

Family Metal Word Sign Color:Hammered Silver True 4x4 and 4x6 postFamily Metal Word Sign Size Options: 23" x 10" 38" x 17" Each sign is made to order in our Madison, Indiana shop. We love creating these unique and decorative signs. They add a neat touch to your home, garage, garden the options are endless. We are a Veteran owned family business and thank you for your business and support. ws 1072