They say:

Based on the same concept and features as the flagship ES-8, the ES-5 is pared down to offer more practical and essential use options for typical guitarists and bassists, and is drastically reduced in size to fit ready-made, standard-size boards. The innovation in creativity of pedalboard systems made possible by the ES-8 has become more available and affordable. Expand your board just by one size and incorporate the ES-5, then you are in for a whole new world of musical expression, not just another utility tool. From this day on, the use of stompboxes will never be the same.