LED bulb doesn’t have any filament to burn out or break; therefore it lasts much longer than a halogen one. Moreover it is instant-on, and thus it is useful in the applications which are subject to frequent on-off cycling. Besides it is plug and play to install requiring no additional equipment. D1 LED bulbs are used in cars with OEM HID headlights.
Also we provide D1 HID bulb. Aside from a LED bulb, these bulbs are easily distinguished by the metal box attached to the actual glass bulb itself. The metal box is an 'igniter'. These bulb types are even cheaper than LED, though they are more expensive than D3 bulbs.
NOTE: D1 and D3 bulbs cannot be interchanged UNLESS their ballasts are replaced with the corresponding bulbs (you cannot mix components from 2 systems together).