What this means

The IEEE assigned the MA-L block 88F9C0 to KTS Kommunikationstechnik und Systeme GmbH. 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 88:F9:C0, it is KTS Kommunikationstechnik und Systeme GmbH hardware.