A clean hinge with a ball for easy posterior-chain work.
The motion is hips back, not knees bending, keep the ball close to your legs.
Pushing your hips back while the ball slides down the front of your legs loads the hamstrings through a long controlled stretch, with the glutes snapping the hips forward to finish each rep. The ball keeps the load centred and close, which makes the hinge easier to learn than with a bar out in front of you. It is the ideal on-ramp to Romanian deadlifts, building the pattern and the posterior chain before heavier tools arrive.
Your hips travel backwards and your shins stay nearly vertical, with only a soft unchanging knee bend. If your knees drift forward and your hips drop straight down, you are squatting. Think of pushing a door shut behind you with your backside.
To wherever your hamstrings hit a strong stretch with your back still flat, usually around knee height or just below. Depth is set by your hamstrings, not the floor. Going lower by rounding your spine trades hamstring work for back risk.
For learning the hinge and for higher-rep hamstring work, yes, especially with a slow three-second lowering phase. Once strict sets of 15 feel easy, the pattern is grooved and you are ready to load the same movement with heavier equipment.
