Voltex/Motex/Scamtex
At best this is a tiny powerfactor correction unit. At worst it's a tiny wall heater with an led nightlight. Cuts 90% off your electrical bill? Er, no. You have more chance of winning the Nigerian lottery with that ticket you never brought than by slashing your electricity bills by using this device. You want money saving tips? Turn off unwanted lights, don't fill your kettle with more water than you need, turn heating & hot water thermostats down a couple of degrees, turn items off instead of into standby mode. Yes, I'm an electrical engineer and received this spam advert the same way you did.