Atari 2600 Accessory

[SL-4042]

Anyone know what this Atari 2600 accessory is?

https://app.box.com/s/fpaebtobvtwaidf5qlzapqg3ceqw726b

[KalessinDB]

Hard to tell from that picture... Is it the system changer?

[Arseen]

My quess would be cart selector, I mean a thing where you plug in several carts and which you then hook into cart slot so you can select game without physically switching carts.

[TDIRunner]

I mean a thing where you plug in several carts and which you then hook into cart slot so you can select game without physically switching carts.

This.