The square speaker grille for 4 inch drivers shall be Lowell Model SG-4. It shall be fabricated from one-piece 22-gauge perforated steel reinforced with a peripheral flange. The grille shall be 7 in. square with a shallow mounting projection of 0.13 in. It shall include 8-32 x 3/4 in. welded studs with nuts for mounting specified 4 in. (EIA 5 in.) speaker. The grille shall also have four 0.218 in. holes on 5.48 in. centers for mounting specified recessed or surface backbox. Grille shall be finished in white powder epoxy and include white screws for backbox installation.