Sigma Engineered Solutions 1-Gang Gray Metal Weatherproof New Work Standard Box Extender Exterior Electrical Box in the Electrical Boxes department at Lowes.com
ReceptXtenders 2-Gang 3/4 in. Electrical Receptacle Box Extension Ring (5-Pack) HD50026 - The Home Depot
STEEL CITY 2-Gang Silver Metal Old Work Standard Box Extender Wall Electrical Box at Lowes.com
How to Use an Electrical Box Extender
Steel City 53151 1/2 3/4 Pre-Galvanized Steel Square Box Extension Ring with 1/2-Inch and 3/4-Inch Knockouts - Ring Terminals - Amazon.com
How to Easily Install an Electric Box Extender – Simply2moms