The Piaggio Liberty 50 uses an HS1 bulb size for both high beam and low beam headlight applications. The replacement chart covers 2018 to 2019 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.
The HS1 is the sole bulb type specified for the Piaggio Liberty 50, serving both the high beam and low beam headlight functions across the 2018-2019 model years.
The HS1 is a dual-filament halogen bulb, meaning a single unit contains separate filaments for both high and low beam operation, which is why one bulb type covers both headlight positions on this vehicle.
The HS1 operates at 12 volts with a 35W/35W output rating, where each wattage figure corresponds to one of the two filaments, both drawing equal power in this case.
The HS1 uses a PX43t base, a three-pin bayonet-style fitting specific to motorcycle and scooter applications. This base type is not interchangeable with common automotive bulb bases such as H4, despite the HS1 and H4 sharing a similar dual-filament halogen design.
The HS1 is built to ECE (Economic Commission for Europe) standards, a regulatory framework recognized across Europe and numerous other markets worldwide, governing light output, beam pattern, and construction requirements.
Because the HS1 PX43t base differs physically from the H4 P43t base, an H4 bulb cannot be fitted in place of an HS1 without a socket adapter, even though both are 12V dual-filament halogen types.