The smoothest squat arc your quads will ever feel.
Stay deep, let your hips travel through the full arc for max quad stretch.
The pendulum squat swings you through a fixed arc that keeps tension on your quads through a huge range, letting you sink into a deep stretch at the bottom with your back fully supported by the pad. The arc matches the strength curve nicely, hardest where you are strongest, so depth stops being scary. Your glutes assist through the drive up, and the whole thing loads your legs hard without asking your spine or your balance to keep up.
Both are supported machine squats, but the pendulum swings through an arc while a hack squat travels on straight rails. Most lifters find the pendulum smoother on the knees with a deeper stretch on the quads.
Low and around shoulder-width to bias the quads, which is what the machine is built for. A higher foot placement shifts a little more of the work to the hips.
As deep as the machine and your hips allow while your back stays on the pad. The bottom stretch is the best part of the movement, so do not cut it short.
