Digivice

The Digivice is available in 2 colours; blue with white buttons as in the picture on the right or orange with blue buttons. This battery-powered machine helps good Digimon "digivolve" into powerful digital monsters. From the black and white screen, select your personal Digimon among eight loyal digi-monsters who are companions of the eight kids from the cartoon. The monsters are Agumon, Gabumon, Biyomon, Palmon, Ganimon, Tentamon, Gatomon and Patamon. You can take your digital monster for a walk by attaching Digivice to your belt or backpack. The more you walk your Digimon, the more power your monster gains. Lead your Digimon through seven areas of the palm-sized, brightly-colored Digivice. When an evil Digimon appears, go into battle and win! You can connect with a friend's Digivice and battle each other too.

Review
Tips for Playing

 

D-3 Interactive Digivice
Info from Digimon Portal

This is a new interactive digivice for the Digimon season 02. The reason it names D-3 is because the new digivice in season two does more than the old digivice. D-3 stands for "Digital Detect & Discover" and "Digimon Detect & Discover (in Japan)." It has a cool design and very similar to the first generation of interactive digivice. There are many type of digimon added to the new digivice. The good thing is that it is compatible to the old interactive digivices for season 01. That's right, you can connect the new digivice to the old interactive digivice that you had to this new one and battle them. It's very similar to the old interactive digivice, so they are probably the same as the old ones. The screen of the Digivice seems to be the same size as the old Interactive Digivice.