Powergrips are a very simple design. Basically it's a fat strap that goes across the pedal (from left-front of pedal to right-rear on left pedal and opposite on the right pedal) at an angle. The riding inserts foot at an angle and then twists his foot (and the strap) slightly to tighten it up. It's simple, but effective. It can't rival clipless for that locked in feel, but in terms of finding a good compromise between performance and convenience, it's a great option.