The MC4 connectors make it very simple to wire two or more solar modules in a series connection. Two wires extend from the junction box, of which one wire is the DC positive (+), and the other is the DC negative (-). The female MC4 connector is related to the positive terminal, while the male MC4 connector is related to the negative lead. MC4 cable is a special connector for solar panels to form an array module, with a reliable connection, waterproof and anti-friction, easy to use, etc. The MC4 has potent anti-ageing and UV resistance. Solar cable is connected by compression and tightening, and the male and female connectors are fixed with a stable self-locking mechanism and. SKU: CT-MC4. GTIN: 840128900659. Be the first to review this product. The MC4crimp allows simple easy to use crimping for common solar cable applications with MC4 style connectors. Lightweight portable style allows for work in hard to reach locations. Crimp Sizes: 2.5 / 4 / 6mm2. Wire Sizes: #26 - 10 gauge wire. The MC4 connectors aren't genuine. This is to be expected in much of the "Solar Connector" products on Amazon, but I expected better from Bluetti. The wires are 16AWG (1.29mm diameter, 1.31mm^2 cross sectional area), which will likely make them the thinnest, and highest resistance wires in the solar setup. The MC4 system is the Army's tactical medical information system including software from multiple sources, future systems and applications, total package fielding and technical support. About MC4, the System. MC4 is a (semi-) ruggedized system-of-systems containing medical software packages fielded to operational medical forces worldwide.