The CB-23 Valor Fitness Back Extension/Sit Up Bench works both sides of your mid section. Lay face down across the stomach pad with your feet securely fastened in the ankle pads and you now do a reverse sit up which means you let your body hand down towards the ground and slowly arch your back in a reverse type sit up motion. Flip over and sit in the small butt pad with your feel securely fastened in the ankle and lean back so the small of your back arches over the larger pad. As you arch your back and lay backwards the larder pad will support your back allowing you to do a sit up from a flat position. These exercises build up and support your core area around your body. The unit is adjustable in size allowing a variety of users to use it.