What this means
The IEEE assigned the MA-L block 4CB99B to WEIFANG GOERTEK ELECTRONICS CO.,LTD. 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 4C:B9:9B, it is WEIFANG GOERTEK ELECTRONICS CO.,LTD hardware.