The short version: a hot swap plate and 24V up converter that lets an ALEXA LF run on standard Gold Mount batteries.
What you'd use it for
The ALEXA LF wants 24V, while standard Gold Mount batteries are 14.4V. This plate bridges the gap: it steps the voltage up to 24V and lets you hot swap batteries without the camera going down.
Good to know
Works with
The ARRI ALEXA LF and Dionic XT batteries.