This mysterious container seems to be much bigger on the inside. What is more, its top seems like it should have something connected to it...
It has a capacity of 9 x 8 (more than 2 normal chests), occupies only 1 space, and doesn't need an empty space above it to open (but see next point).
You can place a Void Interface on top of a void chest, allowing access to any other interfaced chests in the same dimension.
It is not compatible with Inventory Tweaks. The sorting buttons will not appear, and non-vanilla keyboard shortcuts (such as Ctrl+Shift+Click to move all items of a given type) will not work.
When moving your Void chests, remove all enchanted weapons, tools, armor. Currently Void Chests that are broken with a Pickaxe or blown up, will destroy the enchantments that are on your items in that Void Chest.
The Void Chest is the only chest (in the Technic Pack) that has this glitch.