I have use these Speedo Aqua Fit train swim glove for about a week and compare to my previous product with the flimsy nylon top , these baby be substantial . you clearly feel the add pull effort in you shoulder and lat . I measure my palm and I select the medium size . unfortunately the thumb be make for a different primate than I ... LOL . I should have select the large size glove . I can still use they but the construction of the web\/thumb interface negate the benefit of measure you palm as the basis for size . they be make of thick neoprene . I 'll wear these until they wear out then I 'll order a Larger size . I also go with the bright yellow glove as one reviewer think they seem to be construct more solidly . I do not think that have much to do with the thumb\/web issue describe . I can move through the water with normal swimming or use they with my stationary workout in my exercise pool while tethered via a swim belt without any noticeable `` ballooning '' of the glove . they be snug . perhaps they will stretch a little with time . I dry they on a round plastic container for slight stretch . these glove be a excellent value . great offering by Amazon !