This 6-pin Lemo to 4-pin XLR cable is used to provide power to your Battery Plate for Arri Alexa Mini from an external source. The 6-pin end of the cable goes into the 12-14.8v 6-pin Lemo power input port on the battery plate and the 4-pin XLR end of the cable goes into the external power source (such as a camera block battery).
