The included screws are fine for attaching to wood or other soft materials, but if you're using them in a car you'll likely drive them into steel. The plastic case has two "wings" that protrude from each side of the screw hole and are too close to the hole, making it impossible to install a hex screwdriver on a self-drilling metal screw. I carefully sanded the ears and was able to attach them. Since the plastic is transparent you can also see the LEDs, circuit board, at least one resistor, etcβ¦