CONFAST 1/4"-20 x 2-1/4" Male Hurricane anchors install quicker and more efficiently than other storm protection anchoring products. For concrete and concrete block applications, drill pilot hole and drive the anchor in, it's that easy. Use a 3/16" carbide bit for block or a 7/32" carbide bit for concrete. Predrilling is not required in wood base materials. Full thread engagement in concrete, concrete block and wood is required for best performance. Stucco-faced surfaces usually require countersinking so that the top of the hurricane anchors set flush to the stucco surface, allowing for full thread engagement in the base material All CONFAST hurricane anchor installations are required to be compliant with the shutter/panel manufacturer's spacing, alignment and build-out requirements.