Professional Custom Lamp Holder Accessories Manufacturer

Lamp Base:  In the US, "medium" indicates a base that is about 1" in diameter.  Synonyms for medium are "standard", "Edison" and E26 lampholder. It's best to call medium "medium" or "E26" because when other bases are being discussed, the two other synonyms may cause confusion.  Here in the US and elsewhere, there are other screw-thread bases that are prefixed with an "E" followed by a number indicating diameter expressed in millimeters.  "Edison" is medium in the US, but only by general usage and not by any technicality, unless one is inclined to argue (probably unwisely) that E11, E12, etc., is not an acknowledgment of Edison's contribution.

E26 (American) and E27 (European) Edison bases are the same diameter (26.38mm), and only the length of the threaded area is different (26mm vs 27.5mm). Either bulb will interchange perfectly in either type socket.

E26 LED light bulbs and E27 LED light bulbs are Edison based LED lights that have a medium screw base. This is a standard household light bulbs base for traditional incandescent lights. The E stands for Edison and the 26 and 27 refer to the diameter of the screw base. In some, but not all cases an E26 LED light bulbs have a slightly smaller voltage range to include only 100VAC to 130VAC where E27 LED lights will support up to 80VAC to 240VAC voltage range.