Honda Motorcycle Grom 125 uses HS1 bulb size for both high beam and low beam headlight applications. The replacement chart covers 2014-2015 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.
The HS1 is the sole bulb type specified for the Honda Motorcycle Grom 125, serving both the high beam and low beam headlight positions across the 2014-2015 model years.
The HS1 operates on a 12-volt electrical system and carries a dual-filament halogen design rated at 35 watts per filament, meaning both the high and low beam functions are housed within a single bulb unit.
The HS1 uses a PX43t base, which is a bayonet-style fitting specific to motorcycle headlight applications and is not interchangeable with common automotive bulb bases such as H4, despite the H4 also being a dual-filament halogen type.
The HS1 is governed by ECE (Economic Commission for Europe) standards, a regulatory framework recognized across Europe and numerous other markets worldwide, which defines the bulb's photometric and safety requirements.
Because the high beam and low beam positions share the same HS1 specification on the Grom 125, a single replacement bulb type covers both functions, though each position still requires its own physical bulb.