AVR-H128 is inexpensive way to develop and prototype circuits with ATMEGA128 microcontroller without need to deal with SMD soldering. All microcontroller pins are available on extension header with 0.1" and power supply, oscillators, ICSP, JTAG are wired, so all you need to do is to connect your additional components to the AVR ports, as the step is 0.1" these headers perfectly fit the prototype sea of pad boards with 0.1" step.