MULTI-FUNCTION DESIGN: 4 USB charging ports(total output DC 5V/4.2A) and 3 AC outlet Plugs with built-in surge protection. Perfect for smart phones and other rechargeable electronics. PROFESSIONAL SURGE PROTECTION CIRCUIT: Three complementary Surge Protection Circuits, TVS(transient voltage suppressor)+MOV(metal oxide varistor)+GDT(gas discharge tube), with response speed less than 1Ns, and minimum energy-absorbing capacity of 1680 Joules, its response time is much shorter than the traditional MOV surge protection circuit, and it could absorb much more energy from the power spikes. It truly provides great protection of your precious plugged-in devices. COMPACT DESIGN:One-stop wall outlet extended 4 USB ports and 3 AC outlets to save space wall plug,the top slot hold phone when smart phone is charging. Fire-resistant poly-carbon material and high quality components.