On your knees, feet same width as your knees, chest on the Zejax, arms as high as possible, exhale and pull up, inhale and pull down.
You can cheat and use the strength of your legs, but that wouldn't make any sense. Keep your weight in your arms on Zejax as much as you can.
This exercise is found in the program: ZejaX Big, Strong Back Program
Watch a video explaining the exercise in detail: