The seller wanted $20.00, I offered $15.00 since one Joystick was missing. I included a pic with a 2600 Jr for a size comparison. The Flash Back 2 can be modded to accept regular 2600 carts, I am thinking about on doing this, for now enjoying the exclusive games. Meanwhile I modded the Atari 2600 Jr to Composite. I posted a rundown of Atari PlugnPlay systems in the Portable Game Guide.
FlashBack 2 Review: viewtopic.php?f=52&t=33076&p=561423#p561423
Atari 2600 Jr Composite Mod: viewtopic.php?f=52&t=33076&p=561814#p561814

Right Click the images for a larger view
A coincidence that both the Flashback and the original Atari 2600 uses a 9 volt DC power plug. The old Atari's take a mini "Mono Headphone" plug, I had to solder one on.