According to Switronix:
The PocketBase is an all-metal enclosure designed to last through all facets of production. The camera power cable tucks in nicely for camera mounted application, but will also extend up to 24″ for rail mounting. With the ability to hotswap batteries you can continue production without interruptions. Weighing in at less then 1 lbs., the PocketBase is an integral accessory for all your Pocket Camera powering needs.
The PocketBase allows you to power the camera up to 5hrs with two LP-E6 type batteries, while simultaneously charging the removable internal battery. By keeping the internal battery inside the Pocket Camera during operation, you can then hotswap the attached LP-E6 batteries within the PocketBase for continuous camera operation.
Price? About $155 for the PKT-BASEK model (includes battery) and $105 for PKT-BASE. It uses LP-E6 batteries.