Fits perfectly on my swell bottle and I love the flow on mine. My BF says that he would prefer the flow to be a bit more so I guess it's just preference but I like when a bunch of water doesn't come splashing at my face. I do love the connivence of this cap however because it encourages me to drink more water because I don't have to continuously take my lid on and off all the time. It's just a simple click to access my water.