Makey Makey backpacks have invention appeal! Attach any one of these three backpack boards to the black pin headers on the back of your Makey Makey (v.1.4 and higher only!) to access its full set of features. Add a second player to your games, find creative ways to control your computer mouse, and take your inventions to the MAX! Kit Includes: 1x Player 2 Backpack 1x Makey Mouse Backpack 1x Makey Max Backpack 14x Alligator Clip Wires 1x Instruction Card 1x Makey Makey Sticker Documentation: Backpack Landing Page Getting Started with Player 2 Getting Started with Makey Mouse Getting Started with Makey Max Product sheet Product Features Player 2 Breaks out WASDFG key input pins on the back of Makey Makey to alligator clip friendly connections. Indicator LED that is connected to the KEY_OUT pin on the Makey Makey Makey Mouse Breaks out the mouse function input pins (Up, Down, Left, Right, Right and Left Click) Indicator LED that is connected to the MOUSE_OUT pin on the Makey Makey Makey Max Breaks out ALL (keyboard and mouse) of the input pins to alligator clip friendly connections Indicator LEDs connected to both KEY_OUT and MOUSE_OUT pins How to Guides and Activities Visit this link https://makeymakey.com/pages/how-to# Apps Apps to Use with Makey Makey https://makeymakey.com/pages/plug-and-play-makey-makey-apps