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
Crouse-Hinds by Eaton,Four Square Box, 1 1/2 Inch Depth, 1 Gang to 2 Gang, Extension Ring, Steel,TP422
Garvin Masonry Box Extension Ring Two Gang 2-1/2" Deep TBX-225 | Zoro
Commercial Electric 1/2 in. Gray 4-Holes 4 in. Round Weatherproof Extension Ring WRE450G - The Home Depot
TayMac Corp SE450S 4 1/2 Inch Hole Rectangle Box Extension Ring | Quality Electrical Distribution (QED)
4-11/16 in. Square Extension Ring, Drawn, 2-1/8 in. Deep with Eight 1/2 and Four 3/4 in. KO's: Amazon.com: Tools & Home Improvement
Raco 2-1/8 In. x 4 In. x 1-7/8 In. Outlet Box Extension - Bliffert Lumber and Hardware
Octagonal Junction Box Extension Ring - Kraloy Fittings
Steel City 4 in. 1-1/2 in. New Work Deep Pre-Galvanized Metal Octagon Electrical Box Extension Ring 551511234-25R - The Home Depot
Sigma Engineered Solutions Gray Metal Weatherproof New Work Standard Box Extender Exterior Electrical Box in the Electrical Boxes department at Lowes.com
ReceptXtenders 1-Gang 1/4 in. Electrical Receptacle Box Extension Ring (5/Pack) HD50002 - The Home Depot