These high quality ALEKO® rollers to mount vertically on both sides of a gate to help stabilize it from tipping over. They are sold individually but a pair would be required for true stabilization. They are made of UV protected hard plastic. Designed to stand up to the rigors of even the most extreme climates - these rollers will last for years and are maintenance. You can affix them to posts next to your gate via welding or bolting. NOTE: 2 (TWO) ARE NEEDED FOR EACH GATE.