PAR20 led house lights bulbs, E26 medium screw Base LED light bulbs, E26 and E27 are standard medium Edison socket, They has same diameter screw in 26.38mm, Just the length of socket are different, The length of E26 is 26mm, The lenght of E27 is 27.5mm,  They are the normal ubiquitous bulb socket in the world. The E27 Base can replace E26 Base.