This is a half size breadboard with dimension 8.3x5.5 cm. It has two power rails on the sides to allow more than one power level. In addition, it can make the breadboard as thin as 3.5cm and stick it onto an Arduino protoshield by pulling the power rails off easily. With a total of 400 tie in points, all pins are spaced by a standard 0.1" (2.54mm) . It has a self-adhesive on the back and also interlocking parts, so you can hook as many together as you'd like