Drop in Anchors are 1/2" in diameter and utilize a 3/8-16 Hex machine screw for fastening.  They work great with Iron Sleek Hard Court Brackets.  

Simply pre-drill a hole to the depth of the anchor with a masonry bit and drop in the anchor.  After the anchor is inserted, use the Setting Tool to secure it.  The setting tool will engage a tapered slug that will flare out the anchor bottom while securing it to the concrete.   This is a very reliable and easy solution for securing boards to concrete.  This does not work on Asphalt.