Abstract: A large, hollow cylindrical top rail is installed along the top surface of a security fence. The rail has a lengthwise groove and fence post holes cut from the bottom of it. The hollow round rail is placed over the fence and fence posts and secured to the fence by removable fasteners. A spacer may also be inserted between the top of the fence post and the top of the rail to increase the height of the security rail. Lights, security cameras or motion detectors may be placed inside the hollow top rail. Once the top rail is in position, expandable foam is injected into the hollow area of the rail. The foam adheres to the fence and posts and the top rail is permanently attached to the fence. The fasteners may then be removed. The rail is slick, round and approximately a foot in diameter. This precludes anyone attempting to scale the fence from obtaining a handhold on the top of the fence.