The Multi-Functional Electric storage unit, or MFE, is a Tier 2 energy storage device. One MFE is the equivalent of 15 BatBoxes. It is able to store up to 600,000 EU and can accept a maximum power of 128 EU from any of its 5 input faces. Just like the BatBox and the MFSU, it cannot accept any packets with a higher power, but can accept unlimited number of packets (so unlimited EU/t). It can also emit a current of 128 EU/t from its output face, meaning all first tier machines will explode if the output power is not converted through a LV Transformer. Note that the MFE unit will not explode if it reaches its storage capacity. The same applies to the MFS Unit and the BatBox.
Like all storage units, its output face is marked by a special texture (A circle form), which usually faces the player when the block is placed. The direction of the output face can be changed by right-clicking with a bronze Wrench onto any of the input faces of the block; normally, this will point the output face towards the player, but holding Shift while clicking will point the output face in the opposite direction. Be aware that right-clicking the MFE Unit while pointing at its output face will dismantle it.
When redstone is placed in the bottom slot of the MFE, the redstone is burned and used as power for the MFE. Warning: Copper cables and LV Machines cannot handle medium voltage current. Do not try to hook them up directly to the MFE Unit. Use an LV Transformer (and make sure it's facing the right way) or else the machines will explode (luckily the explosion is not as powerful as a creeper explosion, and most likely won't destroy the machines around it, but will still destroy wires and other blocks).
If you use the pick block key on the MFE you get an Iron Furnace.