This device seems to be designed to be attached on top of a Void Chest. It allows you to link other void chests with this attachment into one of six networks of shared inventories.
The Void Interface is classified as Eldritch Knowledge, and must be researched at a Quaesitum prior to being constructed, though it can occasionally be found within monoliths. The Theory to research it is likely or guaranteed to be Tortuous difficulty.
Right-click on a Void Chest while holding an Interface to install it. If a chest already has a Void Interface installed, right-clicking on either the chest or the already-installed Interface while holding a Void Interface will do nothing at all; switch to a different item or an empty slot to access the chest.
Once installed, the interface will display one of six colored runes. This rune shows the network it is conected to. The GUI of the interface also displays this rune, and left/right-clicking on it there will cycle through the available options (right-clicking cycles in reverse order to left-clicking). The interface also has a lever that indicates the number of chests in the net and the number of the chest that is showing. Unlike an Ender Chest, each chest connected to a Void Interface maintains its own separate inventory, and moving items from one chest to another must be done by removing them from one chest's inventory, changing which chest is being looked at, and putting the items in the new chest.
Right-clicking the actual chest will show that chest's inventory, without accessing the void interface in any way. To access the void network, you must right-click on the interface, not the chest.
The Void Interface does not cross dimensions. Interfaced chests placed in the Nether, the End, or Mystcraft Ages all have networks specific to those dimensions, so Void Interfaces do not substitute for Ender Chests.
Wooden pipes attached to the interface or chest only get the items in the chest, not the items on the networks. As with the Void Chest itself, it is not compatible with transposers or other Redpower devices.