It is used on Dynamic bench day according to westside training. It is around 50% of your shirted max or 60% of your raw. 8-12 sets of 3 with 45 seconds in between sets, and each set shoud take you approximately three seconds. It is to build bar speed which should correlate to building a bigger bench if you can get your bar speed better. I think it may work better for shirted benchers as the part of the chest is easier thus the faster you can get it off the chest, the better your chances of competeing the lift. If you want to read more about it go to elitefitnesssystems and read some of their dynamic bench articles.