Heavy Gauge, Extra Flexible Cables for interconnecting batteries, and for connecting inverters. These solar battery cables are also used inside OutBack PSDC and PS2DC enclosures to connect to inverters. We use Extra-Flex Wire rated and UL listed for use as building wire. We mechanically crimp tinned copper lugs with a UL listed crimping system, and finish with heavy-duty color-coded heat shrink. The wire casing on these heavy-duty battery cables is black.