Furmanâs Series Multi-Stage Protection (SMP) circuit also features our exclusive Linear Filter Technology (LiFT) with Extreme Voltage Shutdown (EVS) and a high current TVZ-MOV. Together, these technologies comprise what is, without question, the worldâs most advanced and comprehensive transient voltage surge suppressorSMP (Series Multi-Stage Protection Plus)SMP surge suppression virtually eliminates service calls. Traditional surge suppression circuits sacrifice themselves when exposed to multiple transient voltage spikes, requiring the dismantling of your system, and repair of your surge suppressor. Not so with SMP. With Furmanâs SMP, damaging transient voltages are safely absorbed, clamped and dissipated â no sacrificed parts, no service calls, no down time.