go to goo gle and type in `` shake weight for man review '' choose the second one under amazon which be world of diet . a small word on use both male and female version of this product if you can not figure out how to find the report . while the woman 's version may be only 2.5 pound it cause resistance measure of 32.5 pound . do the math the male version of 5 pound provide 65 pound of resistance . you be not get the full range of motion you would from a dumbbell but what you be get be 3 time the effect in the shorter motion result in better toning than muscle mass . for everyone that be injure it be because you be treat it like a 5 pound weight . there be spring within this thing that cause the resistance measure to hit up to 32.5 to 65 pound when you shake it . treat it like the resistance machine you find at a gym , that line do not weight 100 pound but through resistance it sure as heck can feel like it and give you the same benefit . that be say its the company fault for not appropriately designate the actual resistance this thing cause . again its simulation review not perform by real people but simulation be use in everything these day and the company have a very accurate simulation from what I can tell . be careful when use this product and by all means start out slow until you positive you can use this without get injure . oh and do not forget to stretch before and after like you suppose to else you will get injure as with any work out equipment . eat healthier and stay away from fake butters\/margine , whole grain\/wheat , corn , banana , fast food , and believe it or not orange juice will cause you to gain weight . you will lose weight and build muscle but do not rely on any one thing to get you to where you want to be . like other have say if you want to really get into shape use this in combination with other thing or wait until you endurance be up to the 3-4 time a day thing . slowly pace yourself and you will get there .