Rebaydo P15D-30 2331 LED Headlight Forward Firing 6 to 30 Volt Non Polarity Dual Filament NCNRNW. Works either positive ground or negative ground. Operates full brightness from 6 to 30 volts. Long life up to 30,000 hours. Forward firing so no need to reflect the light off your fixture. The diameter is approximate 1.06". The length is approximately 2.51". The bulb has two holes that the included allen wrench is used to adjust the focused light on the road. The bulb is a NCNRNW which means Non cancelable, No Returns, No warranty. The reason it is a NCNRNW product the P15D-30 flange gets broken when inserting bulb into a P15D-30 socket, please be careful. The contracts are rotated 90 degrees so the bulb is compatible with 2231 bulbs.