H11 bulb size is commonly used for the low beams and fog lights. Kensun offers H11 LED and HID kits. We have H11 LED sets with Cree Chips. These bulbs are designed with the removable locking rings to make the installation easier, so you can fix it in the housing at first and then lock the bulb in. H11 LEDs with ETI Chips come with fixed locking rings. These lights have arc beam covers to provide better light emission. Kensun LED bulbs have 3cm heat sinks with the fan. That is why the cooling system requires additional space behind the headlight assembly to operate properly.There are several options of the HID kits. You can find H11 and H11B sizes. The bulb bases are similar, though there is a difference in the return wire position. The H11 bulb has return wire on the top when installed to the headlight housing, while H11B on the bottom. The reflector housing can take both bulbs and there will not be issues with the light output. As for the projectors, it is important to have H11B. With the return wire on the bottom, there should not be dark spots on the road which you may have with the H11 HID being installed to the projector housing.