UL Fed Spec USB Charger charge ahead with the UL Fed Spec Grade USB duplex receptacle with USB Charging capabilities are designed with strength and durability in mind. They were designed for the commercial market, and are capable of withstanding heavy use due to their UL Federal Specification certification. This product features an improved overall 3.1A USB charging capability, auto-ground clips, zinc-plated ground terminal screw, as well as triple-wipe brass contacts for lasting retention. The screw-pressure-plate back wiring makes installation fast and easy.