While most of the things Mr Sisco promotes are a waste, I have a pair or these hooks and use them all the time. They are made much better than typical 'hooks'. They make the amount of weight I can use for exercises like dead-lifts, shrugs and rows much greater and less limited by grip strength (and with much better form because I'm not fighting with my grip to get the reps out).
There are a couple of things you should be aware of though:
1. If you have small wrists, the cuffs will side down, making them useless. A wrap around the wrist will prevent this from happening. I use weight lifting gloves with a long wrist wrap (Harbinger). Then the hook cuff is positioned about half on my arm and half on the wrist wrap. It won't slide down with this configuration.
2. The 'hook' part can be turned around, so that your fingers go over the hook rather than under it (if that makes sense). This is the most stable positon.
One other thing I'd like to add:
I had a problem with stitching on the first pair I had. I sent an email to the gentleman who sells these hooks and he was genuinely concerned that he might have an issue, so he ask me to return the hooks (at his expense) so he could see what the problem was. He also sent me a new pair with reinforced stitching. This new pair had a similar problem and he sent me a third, even more improved pair. This pair hasn't had the same problem.
This I consider customer service much above the norm.
Anthony