Caches are a type of block added by Thermal Expansion. They store large quantities of a single type of item. Items can be put in or taken out by hand, or automatically inserted into or extracted from any side by other devices.
Caches can be moved around without losing any stored items by dismantling them with a Crescent Hammer. They can only be interacted with when placed in the world, though.
Placed Caches display progress bars that roughly indicate how many items are stored in them. A Multimeter can be used to find out exact item amounts.
Items can be put into a Cache by using it while holding them. This does not work if the Cache is full or set to store another type of item. Using a Cache multiple times causes all matching items in the player's inventory to be put into the Cache.
Using a filled Cache with an empty hand while sneaking locks it to the currently stored item type, so that no other items can be put into the Cache; even when it is actually empty. The Cache can then be unlocked again by sneak-right clicking it with an empty hand again.
Taking items out of a Cache is done by punching it. Full stacks of items are taken out at a time. If the player is sneaking, however, only one item is taken out instead.
Caches follow Thermal Expansion's tier system. The tier of a Cache determines how many items it can store.
The (Basic) Cache can store 10,000 items, the Hardened Cache can store 40,000 items, the Reinforced Cache can store 160,000 items and the Resonant Cache can store 640,000 items. Lastly, the Creative Cache can store exactly 2,147,483,647 items; a practically infinite amount.