What this means
The IEEE assigned the MA-L block 00121F to Harding Instruments. 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 00:12:1F, it is Harding Instruments hardware.
Frequently Asked Questions
Who owns MAC prefix 00121F?
00121F is registered to Harding Instruments 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. Harding Instruments's block covers 16,777,216 addresses.
What devices use 00121F?
Any network device with a MAC address starting 00:12:1F was manufactured by or for Harding Instruments.