What this means
The IEEE assigned the MA-S block 70B3D5E2B to Guan Show Technologe 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 70:B3:D5:E2:B, it is Guan Show Technologe Co., Ltd. hardware.