05-06-2018 09:27 AM
What a great question and we truly appreciate the time that you've spent asking us! Since the NS-48D420NS16 is no longer continued, I was only able to locate the NS-43D420NA18, which should be similar. The NA18 is showing that M4 12MM in lenght are being utilized. I'm hoping that they haven't switched much up with this newer model, and that you're able to find these screws at a local hardware store.
Please let me know if you have any other questions or concerns!