The 8206 Surge Protector is sold as an accessory to the SVP48 and is mounted on the DIN-rail that is a part of that model number. The surge protector helps protect a datalogger against electrical transients. Each surge protector triggers at 110 Vac or 156 Vdc; voltages exceeding those levels are shunted to ground. The 8206 is rated for 125 Vac or 177 Vdc. Voltage limitation is 650 V at 1 kV/microsecond.