Electrical Receptacle Box Extender 3/4" Single Gang Extends Existing Single Gang Electrical Receptacle Box, 3/4" Underwriters Laboratory Listed, 4.7 CI. Easy To Use - Constructed of Non-Conducting Black U/L Listed PVC Material Use This When You Have Applied Barn Board, Even Wainscottings or As a Mud Ring Two 1-1/4" 6/32 Zinc-Plated Steel Machine Screws Included