what is the difference between e26 and a19
A-series light bulb Most A19 light bulbs come with an one-inch long Edison screw base, either of type E26 (i.e. 26 millimeters in diameter) in countries with a mains voltage of 100–120 volts, or of type E27 (i.e. 27 millimeters in diameter) in countries with 220–240 volts AC. A-series light bulbs using the older B22 bayonet twist type base are less common; they can be found in the UK and many British Commonwealth countries.