swim glove provide additional resistance to put more strain on the shoulder , arm , and lat . this build muscle . the glove be size rather inaccurately . I have a `` large '' hand , but the large size be almost too large for my hand . I recommend purchase a size smaller than what one usually use in glove . my only beef be that the velcro closure piece be incorrectly place on the wrist cuff . the velcro should extend farther than it be place on the wrist cuff . the way it be now , very little velcro on the strap engage the velcro on the glove . kone