The Phantomface is a block added by Actually Additions. It functions as a way to interact with items in an inventory surrounded by other blocks. Shift right-clicking a Phantomface and shift right-clicking another inventory with a Phantom Connector will connect them. Items can be pumped in or out of the Phantomface, and those items will be pumped in or out from the other inventory accordingly; the Phantomface acts as an extra 6 sides for the other inventory.
The Phantomface, per default, will have a range of 16 blocks. Placing a Phantom Booster on top of the Phantomface will extend it to 32 blocks. Placing one more Phantom Booster on top of the other Phantom Booster will extend it to 64, and placing one more final Phantom Booster on top will extend it to 128 blocks.