T19 P15D-25-1 base led headlight. Up to 600 Lumen output. Dual filament Low and high beam. Long life up to 30,000 hours. The leds are optically aligned for best led light output using your reflective fixture. Please always clean the fixture when installing led light bulb. Comparable a 25 to 35 Watt halogen or incandescent bulb. The base is T19 P15D-25-1 base.