What this means
The IEEE assigned the MA-L block F4B381 to WindowMaster A/S. Every network interface they manufacture under this block has a MAC address beginning with these digits, followed by a unique per-device identifier. If a device on your network shows a MAC starting F4:B3:81, it is WindowMaster A/S hardware.
Frequently Asked Questions
Who owns MAC prefix F4B381?
F4B381 is registered to WindowMaster A/S in the IEEE MA-L registry.
What does the MA-L registry type mean?
An MA-L assignment, the IEEE's original OUI format, gives the vendor the first three octets and 16,777,216 device addresses under them. WindowMaster A/S's block covers 16,777,216 addresses.
What devices use F4B381?
Any network device with a MAC address starting F4:B3:81 was manufactured by or for WindowMaster A/S.