The JBL MTC-424NC NC NEW-CONSTRUCTION BRACKET is made of flat sheet metal, with wings to attach to the building structure. Holes are drilled for nails or screws at 16 inches (406 mm) and 24 inches (610 mm) on-center. Additional holes can be drilled by the installer at other spacings up to a maximum of 24-3/4" (630mm) apart. Sheetrock installs after the bracket gets installed, and the bracket provides a template for blind cutout of the hole in the sheetrock. For this process, the sheetrock is typically cut with a router-type cutting tool, using the bracket ring as a cutout guide.