the shake weight be exactly what it be advertise to be if use the way it be mean to . many people say that it be not do anything for they and that be probably because they be not use it correctly . you be mean to barely move you arm while you shake the weight . my husband max out at 250 and when he get it on Xmas he use the shake weight for about 15-30 min and he arm be sore the next day . as long as use correctly you will get result .