What this means
The IEEE assigned the MA-S block 70B3D5423 to Harman Connected Services Corporation India Pvt. 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 70:B3:D5:42:3, it is Harman Connected Services Corporation India Pvt. Ltd. hardware.