A:
The Stratus 7 is for a Sirius subscription.
• Sirius satellite receivers — like the Stratus 7 here — receive Sirius subscription service in a band 2320–2332.5 MHz.
• XM satellite receivers — like the ones in GM cars — receive XM subscription service in a band 2332.5–2345 MHz.
I have experience listening to both signals. They both have 12.5 MHz bandwidth (in my descriptions above), but they use their bandwidth differently (to mitigate against signal fading differently), and they use different perceptual audio coding (so they sound different). In my experience, the Sirius signal sounds better than the XM signal with music.
Presently, the Stratus 7 is the only Sirius receiver I see available to buy new. I recommended it for the sound quality of the Sirius signal with music.