4x4 Post Base 4 Pcs, (Inner Size 3.6x3.6) Post Anchors, 13GA Thick Solid Steel & Black Powder Coated,Deck Post Brackets Support Deck Base Plate Pergola Brackets Fence Kit Mailbox MountMaterial Of 4x4 Post Base: Made of Solid Steel, Black Powder Coated, Rustproof and Strong. Deck Post Base Used to support porch railings, pergolas, gazebos, fences, deck brackets, post brackets and mailbox post brackets. Unique design: There is a partition at the bottom of the 4x4 post base, which is designed to be completely separated from the ground. Long term use will not cause the wood to rot due to rain. There is a small square box in the middle