This is the SANWA SUPPLY energy-saving watt monitor, model TAP-TST8N. It was only used as a tester in areas where circuit breakers tend to trip. It can be used as an energy-saving meter. There are no particular operational issues, but since it is a used item, please purchase only if you understand and accept the "no claims, no returns" policy. - Brand: SANWA SUPPLY - Model: Watt Monitor - Maximum Output: 1500W - Voltage: AC100V