#1157 6 Volt Positive or Negative Chassis vehicles, trucks and tractors. Up to 500 Lumen output. BAY15D base meaning two contact and the bayonets are offset. This is a two filament C-6 Design. Since there are two filament one if for tail light and one is for brake light or turn signal. The leds are optically aligned where the original filaments would be so the light output is maximized and not wasted. This bulb diameter is smaller than a normal #1157 and the length is the same so you should not have any issues installing the bulb. The bulb is available in white 6K, warm white 3K, Red 625 nm, Green 526 nm, Blue 464 nm & Yellow 594 nm. Long warranty please see bottom of the page for more warranty information.