The Xact XTR3 is a Sirius satellite radio with a unique flat design that's made to be slipped above the visor in your car. It's a plug-and-play Sirius model, which means the head unit goes where you do, plugging into a car adapter (included) or home adapter (the XS052--sold separately), so you can listen on or off the road. The XTR3 is widely available for about $50.
Upside: Like all plug-and-play models, the Xact XTR3 lets you listen to the dozens of Sirius satellite music, news, talk, and sports stations wherever you go (assuming you invest in suitable docking stations) while paying only a single-subscription price of $13 per month. It also includes an FM transmitter, so rather than using a cassette adapter or a line-in port, you can hear your Sirius stations rebroadcast to any nearby FM radio. The XTR3 can store 36 channel presets.
Downside: The Xact XTR3 is a basic satellite radio; it's lacking the buffered memory for rewinding, recording, and playing back programming that you'll find on more advanced models. And while it can be mounted on a dashboard with the included stand or slipped above a sun visor, you'll still need the power adapter running to the cigarette lighter, which could be more cable clutter than you prefer in your vehicle. And while it's transportable, the XTR3 isn't an MP3-enabled portable unit such as the Sirius S50, which you can slide in your pocket to listen to prerecorded (but not live) satcasts. And if the low price seems too good to be true, remember that you'll need to factor in the monthly subscription, as well as any of the extra accessories you might require to listen to the Xact XTR3 away from your car.
Outlook: The Xact XTR3 lacks cutting-edge features found on other plug-and-play or transportable Sirius models, but it's a perfect option for Sirius listeners and Howard Stern fans who plan on listening in the car and prefer its visor-friendly form factor.