B-124E can only function when connected to a B-124, and is not a standalone product.
But what if that wasn't enough? If the battery life of the B-124 unit alone isn't enough for you, you can extend it using the Power Magic Expansion Battery Expansion Pack (B-124E). This Expansion Pack doubles the energy stored, allowing the B-124 system to last for more than double the amount previously stated. Multiple Expansion packs can be chained together to create a system that can last for as long as you desire!