The classic-style Flash Collar is the most popular collar for in-ground flagpole installations. Remember on ground installations, the outside diameter of the collar should be at least 1 in. larger than the diameter of the foundation sleeve. The inner diameter of the collar will be approximately 1/8 in. larger than the shaft. At installation, spaces should be sealed to prevent water from entering the ground sleeve. The flash collar stands 2-1/2 in. tall and is available in a variety of options. The Spun Aluminum is approximately .060 in. thick. The Cast Aluminum and Fiberglass are approximately 1/4 in. thick. The Split version has a hidden bolt. See below for related products.