LED strip lights most commonly operate on 12 or 24 volts of direct current from a power supply, sometimes referred to as a driver. USB strip lights operate on the standard 5-volt direct current used by USB devices. Mains voltage LED strips are also available. These have the advantages of being usable in much longer single runs without a brightness drop along the length, but are less flexible and heavier due to higher voltage and current ratings and thick coatings for shock safety and high IP ratings in their intended outdoor positions, with limited cut points.