IN MOST CASES, NO BRACKETS OTHER THAN THE ONES INCLUDED WITH YOUR CONTROL400 SERIES SPEAKER ARE REQUIRED. Everything needed for most installations of these loudspeakers is provided with your Control Contractor ceiling speaker. However, a particular procedure that is sometimes used for installation into sheetrock (typically gypsum board) can be facilitated by the use of JBL’s optional pre-installation brackets before the sheetrock is installed. The pre-installation bracket provides a bracket to which wiring can be strapped in-place behind the sheetrock. It can function as a cutout template when many cutouts are to be made in a production-line style installation. And it can reserve a location in the ceiling prior to the sheetrock getting installed. The optional 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 inches (630 mm) 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.