Harley-Davidson FXLR Low Rider 107 Turn Signal Bulb Size

Harley-Davidson FXLR Low Rider 107 rear turn signal bulbs utilize a P21W bulb size for replacement applications. The replacement chart covers 2018 to 2020 vehicle production years with corresponding bulb size specifications.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Rear Turn Signal

Years	Bulb Size
2018-2020	P21W

Bulb Specifications

Description	Bulb Size
ECE standard (Europe & worldwide). Single-filament signalling bulb with BA15s bayonet base. 12V, 21W.	P21W

Other Locations

Additional Notes

The P21W is the rear turn signal bulb used across all listed model years of the Harley-Davidson FXLR Low Rider 107, covering the 2018-2020 range.
The P21W operates on a 12-volt electrical system and draws 21 watts, which places it in the standard wattage range for single-filament automotive signalling applications.
As a single-filament bulb, the P21W is dedicated solely to one lighting function, meaning it does not share its filament between turn signal and brake light duties as a dual-filament bulb would.
The P21W uses a BA15s bayonet base, where "BA15" refers to the 15mm pin spacing of the bayonet cap and "s" denotes a single contact at the base, distinguishing it from the dual-contact BA15d variant.
The P21W is governed by ECE regulations, a standard recognized across Europe and numerous other markets worldwide, which defines its output and performance tolerances.
The BA15s base is not interchangeable with the BA15d base despite sharing the same 15mm pin geometry, as the contact configuration differs and substituting one for the other would result in an improper electrical connection.