In this video, you can see the technical execution of the Box Squat from a front view and side view.
Notice the contact with the box, as compared to Box Squat variation 1, the contact is longer, and Niek uses the momentum of the upper body to overcome inertia and get off the box.
This variation can be used to reduce the stretch-shortening cycle and work on concentric strength, as well as training a powerful hip extension.
This variation is most often done at a knee angle of 90 – 100 degrees, and sometimes with added accommodating resistance, such as resistance bands.
However, the height of the box can vary depending on your needs and goals from 60 degrees knee angle to 120-degree knee angle of more.