Universal Parts BAY15D Tail & Brake Light Bulb - 12V 21/5W

This Universal Parts tail and brake light bulb restores running-light and brake-light illumination in one straightforward replacement. Its dual-filament 12V 21/5W design fits matching BAY15d sockets on scooters and other powersports equipment, including CSC go. scooters and compatible 139QMB and GY6 models.

Key Features

• Two lighting functions: A 5W filament provides the running light, while the 21W filament provides the brake light.
• Universal socket-based fit: Suitable for scooters and other powersports equipment requiring a 12V 21/5W BAY15D bulb.
• Dual-filament incandescent design: Clear glass bulb with separate tail- and brake-light filaments.
• BAY15d bayonet base: Double-contact base with offset-height retaining pins for a matching socket.

Technical Specifications

• Brand: Universal Parts
• Part number: 0900-4021
• Alternate references: 138-37-10PCS, 138-37-1PC
• Voltage: 12V
• Brake-light filament: 21W
• Running-light filament: 5W
• Base: BAY15d (1157-style), double-contact bayonet
• Base diameter: 15 mm
• Retaining pins: Offset in height, one higher than the other
• Base contacts: 2
• Light source: Dual-filament incandescent
• Glass: Clear
• Quantity: 1 bulb

Compatibility

Universal replacement for scooters and other powersports equipment using a BAY15d socket and requiring a 12V 21/5W dual-filament tail/brake bulb. Commonly found on 139QMB and GY6 model scooters; fitment is determined by the bulb socket, voltage, wattage, and housing clearance, not the engine alone.

How to identify the base: The BAY15d (1157-style) base is 15 mm in diameter, has two electrical contacts on the bottom, and uses two retaining pins at different heights. Compare these details with your original bulb and socket, then confirm the 12V 21/5W requirement and bulb clearance. BAY15d and BA15d are different base specifications; this bulb requires a BAY15d socket.

• Universal replacement for matching BAY15d sockets
• 12V dual-filament incandescent bulb
• 21W brake-light and 5W running-light filaments
• Fits CSC go. scooters
• For scooters and other powersports equipment requiring matching bulb specifications

Brand: Universal Parts; Part number: 0900-4021; Alternate references: 138-37-10PCS, 138-37-1PC; Voltage: 12V; Brake filament: 21W; Running filament: 5W; Base: BAY15d double-contact bayonet with offset-height pins; Light source: dual-filament incandescent; Glass: clear; Quantity: 1 bulb

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