I've had my powerball for 3 months or so now and I love it, it has increased my golf drive by around 30 or so yards, the dexterity of my wrists has increased greatly and best of all it's fun to use. This 'knack' to using a powerball is simple, dont be disheartened if you cant get it to work at first, it took me around 3 days to get it working and eventually you can learn to start it without using the chord.
Must buy for anyone looking to increase their arm muscle (significantly) and have fun doing so. As said earlier if it were around 12.99 I would say stop reading now and click buy. As for the price that it is stated I would say stop reading now, think for 10 seconds or so, then click buy.