The Lexus IS F uses the 7440NA bulb for both its front and rear turn signals across the full 2008-2014 production run.
The 7440NA is a single-filament wedge-base bulb built to the T20 form factor, which refers to its wedge-style base and overall envelope size.
It operates at 12 volts and draws 21 watts, which is a standard wattage for incandescent turn signal applications in passenger vehicles.
The "NA" suffix in the 7440NA designation indicates natural amber glass, meaning the amber color is produced by the glass envelope itself rather than by an amber-tinted lens or housing.
The 7440NA conforms to ANSI standards applicable in the United States and Canada, classifying it as a North American market specification bulb.
Because the same 7440NA bulb is specified for both the front and rear turn signal positions, a single bulb type serves all four turn signal housings on the vehicle.
The 7440 base type is a single-filament wedge, which is not interchangeable with dual-filament wedge bulbs such as the 7443, despite sharing the same T20 form factor and physical base fit.
The natural amber glass of the 7440NA is a fitment consideration when the vehicle uses clear or white-tinted lenses, as substituting a clear-glass 7440 would alter the emitted light color and may not meet regulatory requirements.