ALUCSET 3 Pack Medium Screw Base to Medium Base Light Bulb Socket Porcelain Extender, E26 E27 to E26 E27 Lamp Bulb Socket Extension Adapter, (Set of 3, Porcelain E26 Extender): Amazon.com: Tools
Socket Extender - Growlite
Amazon.com : E26/E27 Light Bulb Socket Extender Adapter, E26/E27 To E26/E27 Flexible Extension, All-Directional Light Adjustable Converter For A19 Led Lamp,Recessed Spotlight Etc. (4-Pack) : Tools & Home Improvement
E26 to E26 Socket Extender,TWDRTDD E27/E26 to E27/E26 Lamp Holder Adapter (3Pack) - - Amazon.com
Leviton Medium Base Socket Extender R52-02006-000 - The Home Depot