Elon Musk recently clarified that Tesla’s new 4680 cells are already being deployed in some of its vehicles as prototypes. Even more interesting is that the next-generation batteries have already been in use for several months, though the CEO did not state which of its vehicles are equipped with the 4680 Roadrunner batteries.

The Tesla CEO related his update in a recent post on Twitter. While responding to a question about the company’s strategy with its cathodes and its suppliers, Musk noted that Tesla’s own battery cells are already powering some of its cars. That being said, Musk clarified that ultimately, prototypes such as cars that currently run on the company’s 4680 cells are trivial, as they are incomparably simpler than actual volume production.