The device slips into the cartridge port and wraps around to cover the bottom of your DS Lite/DSi/DSi XL/3DS where it contains three slots for both DS and 3DS cartridges and a three-position slide switch that designates which of the games is currently being piped into the handheld system.
The Universal Game Selector really is a simplistic design and results in good device that does just what is advertised. You do have to treat the device a little differently between the different DS's, but that is primarily because of how the different systems handle the changing of games.
The DS Lite didn't allow for the switching in and out of games while the system was on, so the Universal Game Selector isn't quite as impressive on the older handheld since you have to turn the system off before moving the switch, and then turn it back on.
For the DSi, DSi XL and the 3DS, the Selector works just fine since the systems allow you to pop the game out and put it back in while on the Home Screen. There are a few other conditions to cover, but we will talk about them later in the review.