This is a machine that should be used judiciously with very specific clientele with very specific range of motion.
Besides for its limited functional transfer to real-life need, this VIDEO demonstration shows the lumbar flexion (under load) at the bottom of the movement.
NO GOOD for the lower back.
I’ve had many clients with lumbar problems flare up because of this machine (and they can’t understand why)…this video does a good job of illustrating it.
Your best bet for leg strength and development? Save your spine and modify the squat to fit your capabilities.