To protect the prime mover in the bench press we must obtain enough spinal extension and leg drive to create torque. The heels are down and drive hard into the floor, the lower back is arched from scapular retraction and depression which activates the lats and allows for stabilization of the shoulders. As the bar is eccentrically lowered, think of pulling the bar into you while the shoulders are down and externally rotated. This form goes for any bar or dumbbell unless you wanted to flatten the lower back into a surface to further work on bracing the core and flexion.