What is the Size of the White Screw on the Phone Mount Adapter?

The white screw on the Phone Mount Adapter is an M4 × 8 mm nylon screw.

If you are not in a hurry, you can also purchase a 5-pack of M4 × 8 mm nylon screws from us.
Alternatively, you can search for M4 × 8 mm nylon screws on Amazon or eBay.