The Sirius Mobile Docking Station. SM4000, is for use with the Sirius Orbiter receiver SR4000 both of which are manufactured by Radio Shack.  The unit, when brand new, comes with a low profile antenna with 21 feet of cable, quick-release windshield mount, audio cable, and a car power adapter.  The unit also has a built-in 4 frequency FM transmitter (88.1, 88.3, 88.5, 88.7).  This eliminates the need for any hardwiring to your vehicle's existing stereo.

One of the main drawbacks to this item is that it prevents venting of the receiver.  When the receiver is placed in the docking cradle, it blocks the vents on the lower half of the SR4000 which in turn prevents adequate air flow and causing high amounts of heat to build up.  This can eventually cause damage to the receiver.

When looking to bid on or purchase one of these units used, be very cautious.  Make sure the antenna is included and is in working order.  Also, verify with the seller that the unit DEFINITELY HAS the built in FM transmitter.  There is a seller, consumersolutions,  that is selling a modified version that DOES NOT have the FM transmitter but does claim that the units have it.  Their units also do not come with an antenna or car adapter or windshield mount, but does have an AC power adapter and an audio cable.  This makes the mobile dock useless in your vehicle and almost ready for home use only.

I highly recommend not to buy this product used.  Contact your local Radio Shack to purchase the item new or refurbished or only bid on the product that is still in original carton.  Good luck!