Specialized MoFlo Bottles are an upgraded version of the original Little & Big Mouth Water Bottles. They now have the MoFlo cap, like the Purist has, for a higher flow-rate and softer poppet. Wider throat diameter for easier cleaning and for adding ice. Lighter and more flexible material, 6 grams lighter, to be exact, and easier to squeeze. Still fits all types of bike bottle cages and fanny pack/bottle carriers.