What this means

The IEEE assigned the MA-M block B4ABF3E to RANG DONG LIGHT SOURCE & VACUUM FLASK J.S.C. 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 B4:AB:F3:E, it is RANG DONG LIGHT SOURCE & VACUUM FLASK J.S.C hardware.