This workout targets the chest from top to bottom by utilizing various bench angles. (build-muscle-and-burn-fat.com)
Bench angles between 30 — 56 degrees appear to produce greater clavicular head EMG amplitudes compared to angles either above or below this range (Barnett et al. 1995, Lauver et al. 2015, Trebs et al. 2010, Luczak et al. 2013). (strengthandconditioningresearch.com)
Assessing the effect of bench angle, Barnett et al. (1995) found a difference between 40 degrees (superior) and -18, 0 and 90 degrees. (strengthandconditioningresearch.com)