They are these sound bars on Amazon. I will say that these things are incredibly over-priced for what they are. That said, right now they are almost $10 off for Prime day so I ordered a couple more yesterday. Still, $35 each is more than I'd like to pay.

If you're serious about getting some of them, I'd recommend checking out alibaba. I've found very similar ones on there for much cheaper, and some of them have more features than the ones being sold on Amazon (like an on/off button). These things are so overpriced that I've been considering ordering a pallet of them and selling them on Amazon - it'd be easy to undercut the price they are selling these at and still make a decent profit.