For the vehicles take 9007 or 9004 bulbs, some of them have a retainer/locking ring, which would secure the original bulbs into the lighting assembly. Normally, the retainer ring has two types, here are the images of them:
If your retainer ring is type 1, while installing the LED bulbs, you need to remove the white collar on LED bulb(turn it to the open then slide it off), and install the retainer ring from the front, then put the collar back on.
1. Firstly, take off the plastic locking ring from the bulb.
2. Put the ring together with the original locking ring of your car.
3. Insert the bulb into the two rings.
4. Insert the bulb with the rings into the light housing.
5. Rotate and lock the bulb.
By following our instruction, One of our customers installed the LASFIT LAplus 9007 bulbs on his 2003 Ford Explorer Sport Trac within 10min. What a great job!
However, if the retainer ring is type 2, a little bit longer than type 1, then you have to modify and cut the retainer ring, to get it fit into the LED bulb.
Here is what the customer Andrew did for his Ford F150 1991.