Allright , I have purchase the female shakeweight for my wife , and she absolutely love it . after give it a shake , I decide to go out and purchase the man 's one . after use the man 's one for less than a week , the Shakeweight begin to make some horrible noise , and I call they to ask they about this . apparently , something have come loose within the inside , cause it to make a racket whenever I shake it . now , I know it take lot of technique to shake this and keep it still , but even if you do not do it right , I do not think it should break . so , bear in mind that the Shakeweight be subjective to damage , as the more you use it , the more noise it will make . after use the female one interchangeably with the man 's , I have notice some noise come from it too . my belief be that the Shakeweight have some potential problem , and you 'll probably have to get it warranty out a few time within a year time span . do it work ? yes , I believe it work quite well , despite the problem I have have with it . I like use it , but problem plague its construction . so keep this in mind when purchase it .