This is our 12' length x 1-3/8" diameter (3.7 m X 3.5 cm) 17-gauge galvanized steel fence top rail. It is part of the fence framework and helps support the chain link fence fabric.This top rail runs horizontally and connects the terminal posts and the line posts. It can be used with all heights of chain link fences and can easily be fit together to extend to any length of your fence. The heavier gauge post helps provide strong fence framework. Extremely durable and corrosion resistant.