It looks like you can get them here http://www.strength-shoes.com I have to admit the website looks a little bit shady. Personally, I'd go with a more reputable place like eastbay instead of trying to save $5. Your call though.

I've never used them myself(didn't need to hahaha), but I've heard that they work well. Between a regimen of using these, and spending time stretching your calves and/or doing heel raises, I've heard many stories of these increasing vertical hops by 5-7 inches. In truth however, there are more gains to be made by on-court decision making than strictly through physical ability.

Are strehgth any good ,how much higher can you jump,how long you must ues it to jump higher