Metal-Fab 5MH Style "M" B-Vent Hanger/Wall Band. These light commercial and residential B-Vents feature a positive twist locking system designed for easy assembly and dis-assembly without bending or harming the product. The B-Vent Locking System comes standard on 3"- 6" pipes. The Metal-Fab 5MH Style "M" B-Vent Hanger/Wall Band connects to the outside wall and provides a 1" clearance and extra stability. For correct installation and maximum support, install a band every six feet.