The Double Arm Snatch works through the entire posterior chain, including the glutes, hamstrings and erectors, all of which are vital in hip extension. The upper back is also worked to stabilise and produce force.
Stand with your legs just wider than hip width apart. Bend down, keeping your back flat and grab the weight(s). From here you are going to powerfully bring the arms up all the way through, coming close to a clean position, but not pausing the movement until both your arms are pressed into the air above your head.
You should ensure you are bending your knees at the bottom of the movement rather than creating a bend in your spine and you should maintain a subtle bend in your legs throughout.