The Nill Building Solutions Flush Mount Concrete Anchor Flange is perfect for all concrete applications. Our flange and caulk groove provides superior strength and 100% waterproofing protection. The waterproof internal threaded port allows you to bolt any attachment into this product. The allen key insert insures easy installation for every application. A 3/8”-16 bolt threaded into this product will give you the holding power of a ½”.