This allows you to hook up all kinds of things as an input.It is an invention kit that tricks your computer into thinking that almost anything is a keyboard.The kit uses high resistance switching to detect when you've made a connection even through materials that aren't very conductive.The on-board ATMega32u4 communicates with your computer using the Human Interface Device (HID) protocol which means that it can act like a keyboard or mouse.size: 9.4cm x 4.8cmMaterial:PCcolour:As ShownPackage Contents:2 x main control board20 x spring clips2 x 20 x jumpersOnly the above package content, other products are not included.Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.