Front-rack squat with a box to lock in your depth.
Touch the box under control, don't crash and bounce off it.
With the bar racked across your front delts, your torso has to stay bolt upright, which shifts the workload squarely onto your quads. The box behind you sets a non-negotiable depth and forces a controlled sit back, then your glutes have to fire hard to drive you off it without any bounce or stretch reflex to lean on. It earns its place when you want honest depth, a stronger bottom position, and quads that can stand up out of a dead stop.
One that puts you at or just below parallel when you touch it. Lower boxes build more range and are harder, higher boxes suit heavier loading or lifters working around mobility limits.
Touch it under control and stay tight, a brief settle is fine but never relax onto it or rock forward to build momentum. Crashing down and bouncing off defeats the point and beats up your spine.
The box standardises every rep's depth and kills the bounce, so you learn to produce force from a dead bottom position. It's also a great teacher if you tend to cut front squats high without noticing.
