Portable subscription cartridge that plays XM Satellite Radio through multiple XM Ready home audio systems ** Small and lightweight design makes it convenient to carry (keychain holder included) ** Listen to XM in your home, office or elsewhere through the many available XM Ready home audio systems, all for one monthly subscription ** Compatible with a growing number of XM Ready home audio systems **** CNP-2000H required, as well as an "XM Ready" Home Audio Receiver ****