Trex composite posts and related products provide support for Trex w/Horizons fence systems and gates. Shop for the various fence post components here. Trex composite posts can also be used for other applications such as the Seclusionsfence system, ornamental iron or aluminum fencing, even as an upgrade for wood fences. No rust, no rot and no twisting, splitting, splintering! Trex posts do not require internal support for fences up to 8ft tall. Post stiffeners are available for gates and taller fence configurations.