Ski-Doo Formula STX Brake Bulb Size

The Ski-Doo Formula STX brake requires a 1157 bulb size for proper operation and illumination. Data for the specified component covers the range from 1994 through 1996.

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

Bulb Size by Year Range

Years	US Type	EU Type	Shop
1994-1996	1157	P21/5W	Check Price

Bulb Specifications

Description	Type	Shop
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. 12V, 21W/5W.	1157	Check Price
ECE standard (Europe & worldwide). Dual-filament signalling bulb with BAY15d bayonet base. 12V, 21W/5W.	P21/5W	Check Price

Other Locations

Additional Notes

The 1157 is the brake bulb size specified for the Ski-Doo Formula STX across the 1994-1996 model years.
The 1157 is an ANSI-standardized bulb type recognized across the United States and Canada, which reflects a widely adopted specification in North American vehicle lighting.
As a dual-filament bulb, the 1157 operates two separate filaments within a single envelope: one rated at 21W for high-intensity functions such as braking, and one rated at 5W for lower-intensity functions such as running lights.
The 1157 uses a BAY15d bayonet base, a two-pin offset base design where the two pins are positioned at different heights to prevent incorrect insertion orientation.
The bulb operates on a 12V electrical system, consistent with the standard voltage found in most powersport and automotive applications of that period.
Because the BAY15d base uses offset pins, substitution with single-filament bayonet bulbs or those with symmetrically placed pins is not compatible, as the physical keying of the base prevents interchangeable fitment.