Bulb shapes and bases, drawn to scale

Every GREENIC screw-in bulb has an E26 base. What changes is the shape above it, and that decides which fixture it fits.

Drawn to one scale from the sizes the brand publishes for its colored bulbs, UV BR30 bulbs, red flood bulbs. The A21 radar bulbs are slightly larger than an A19.

E26 is the standard medium screw base in American homes, 26 millimeters across. Every screw-in GREENIC bulb uses it, so the question is never the thread. It is the space above it.

An A19 is the everyday pear shape. It fits table lamps, most ceiling fixtures and porch lanterns. A BR30 is a wide reflector bulb for recessed ceiling cans. A PAR38 is a heavy flood bulb for outdoor holders and deep cans. It will not fit under most lamp shades.

Measure the inside of a closed fixture before you choose. A bulb that touches the glass runs hot and the glass can crack.

Sizes as published by the brand.
ShapeWidthHeightWhere it goes
A192.36 in4.13 inLamps, ceiling fixtures, porch lights
BR303.7 in5.2 inRecessed ceiling cans
PAR384.7 in5.7 inOutdoor flood holders, deep cans