12" x 8" THRU-WALL REGISTER BOX - RETURN AIR TRANSFER BOX

Design includes 1/2" drywall lip on both sides of boot and rounded flange corners for added safety.
Opening 1/4" oversized to accommodate register/grille.
Dual Bead design for added strength.
Black diffuser board coated with EPA registered anti-microbial protective acrylic agent along air stream side.