Raco 665 4" x 2" Steel Handy Box Extension, 1-7/8" Deep, 1/2" End Knockouts | Quality Electrical Distribution (QED)
Carlon Multi-Gang PVC Electrical Box Extender (2-Pack) B1MGEXT-2 - The Home Depot
ReceptXtenders Receptacle Outlet Box Extender, Electrical Outlet Extender for Electrical Box and Electrical Outlet Switches, UL Listed - 1/2" Single Gang 5-Pack - Amazon.com
iMBAPrice BE1-1 (1-Gang) Electrical Power Outlet Box Extender - White (Made in USA) - Walmart.com
Southwire 4 in. x 1 in. Metallic Steel Switch Box Extension Ring Box Conduit Fitting Accessory SBEX-UPC - The Home Depot
Thomas & Betts (T&B) IHEF2-1 Electrical Box Extenders - Interstate Electric Supply
Box Extenders - YouTube
Steel City Southwire Drawn 4 In. x 4 In. Square Box Extension | Morganfield Home Center
TayMac Corp SE450S 4 1/2 Inch Hole Rectangle Box Extension Ring | Quality Electrical Distribution (QED)
3 Gang Electrical Box Extender Goof Rings Add Up to 1.5'' Deep