Both are correct. They mean slightly different things:
Fitting is E12 (socket size)
Form factor is B39 (bulb shape)
Both help identify this bulb.
Here are the full specifications:
White ambiance specs:
Fitting E12
Form factor B39
Lifetime 25000 hour(s)
Color temperature 2200 - 6500K
Wattage 6 W
Input voltage 110V-130V
Light output All shades of white
Software upgradable when connected to Hue bridge
Height 39 mm (1.46 inch)
Width 114 mm (4.5 inch)
Max. operation power 6 W
Max. standby power 0.1 W
White and color ambiance specs:
Fitting E12
Form factor B39
Lifetime 25000 hour(s)
Color temperature 2200-6500 K
Wattage 6.5 W
Input voltage 130V
Light output 16 million colors
Start up Instant 100% light output
Height 39 mm (1.46 inch)
Width 114 mm (4.5 inch)
Max. operation power 6.5 W
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