The Vespa S 50 4V headlight bulb uses an HS1 size for both high beam and low beam functions. The replacement chart covers 2010 to 2014 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 Vespa S 50 4V uses the HS1 bulb type for both high beam and low beam headlight positions across the 2010-2014 model years.
The HS1 is a dual-filament halogen bulb, meaning a single bulb contains separate filaments for both high and low beam functions within one unit.
The HS1 operates at 12 volts with a 35W/35W rating, where each wattage figure corresponds to one of the two filaments.
The HS1 uses a PX43t base, which is a bayonet-style mount specific to motorcycle lighting applications and is not interchangeable with common automotive bulb bases such as H4.
The HS1 is governed by ECE standards, a regulatory framework recognized across Europe and numerous other markets worldwide.
Because both the high beam and low beam positions share the same HS1 specification on the Vespa S 50 4V, a single replacement bulb type serves both functions in the headlight assembly.