Koito 1157 Dual Filament Brake Tail Light Bulb BAY15D

The Koito 1157 is a premium dual-filament halogen automotive bulb designed for brake lights, tail lights, turn signals, and other rear lighting applications. Manufactured in Japan by Koito, a trusted OEM supplier to major automotive manufacturers, this bulb delivers reliable performance and superior quality.

Key Features:

• Dual filament design with BAY15D double contact bayonet base for two-level brightness operation
• 21W/5W power rating (P21/5W designation) for high and low filament operation
• 12-volt operation for standard automotive electrical systems
• S25 bulb shape with precision-engineered glass envelope
• Tungsten filaments surrounded by argon gas for extended lifespan
• Compatible with 1157, 2057, 2357, 7528, and other equivalent applications
• Twist-lock installation for secure mounting

The 1157 bulb features two filaments that allow it to serve dual purposes: the higher-wattage filament operates when braking or signaling, while the lower-wattage filament provides running light or parking light functionality. Koito's manufacturing precision ensures consistent light output, proper beam pattern, and resistance to vibration and thermal stress. Ideal for cars, trucks, motorcycles, RVs, and trailers requiring a reliable replacement bulb with OEM-quality construction.