Power Hooks stay with your dumbbells and hang onto any overhead barbell. This puts you in proper lifting position without having to lift the dumbbell from the floor nor having to drop them back onto the floor after the exercise. Power Hooks also provide a better way to handle and spot dumbbells.

The only slight negative I have is being brought up in an "old-school" gym environment being told "If it's too heavy to get in position, it's too heavy too lift!". In short, learn the right technique to get the weight in position and you should be able to press the same weight once it's there. This theory's always proved pretty sound and it does frustrate me seeing weights constantly being awkwardly placed in a start-position by a spotter and then dumped on the floor at the end of a set - it's just not good gym etiquette.

The above aside, why do we advertise Power Hooks? It's a good idea! Assuming you've always used good techique to assume a start-position and put the dumbbells down correctly at the end of a set, you may well of picked up a niggle at some point (lower back, shoulder) that is aggravated not in the dumbbell press exercise itself, but in the pre or post manoeuvring. In this instance, they seem like quite a good idea. I would just train within a sensible weight and rep range in order that you can ensure they are re-racked correctly at the end of your set.