Elon Musk and Tesla are cooking up something for late April, and it’s not a new car.

“Major new Tesla product line – not a car – will be unveiled at our Hawthorne Design Studio on Thurs 8pm, April 30,” said Musk in a tweet.

Major new Tesla product line — not a car — will be unveiled at our Hawthorne Design Studio on Thurs 8pm, April 30

— Elon Musk (@elonmusk) March 30, 2015

So, what’s Tesla up to? Probably a home battery.

You’ll recall that Tesla has been working on a lithium-ion battery for home energy storage for some time, and at the company’s earnings call in February Musk set a “couple month” timeline on the big reveal.

“We’re going to unveil the Tesla home battery, or the sort of consumer battery that will be for use in people’s houses or businesses, fairly soon. We have the design done, and it should start going to production, probably in about six months, or so. We’re trying to figure out a date to have the product unveiling, but it’s probably in the next month or two months. And it’s really great; I’m really excited about it,” he said at the time.

Of course, it could be a motorcycle. Stay tuned.