The H2O’s are a Heavy duty stand alone hydration system. The H2O bladder is double ply to withstand rough use and give long life to the system. The H2O is a great upgrade to your current hydration carrier. The 2 liter model will fit in most all other brands of 70 oz. hydration carriers, while the 3 liter model will fit in most of the larger carriers. The H2O’s offer all the great features of the Source hydration systems such as the Mark Two Valve, braided tube cover and the easy fill screw cap. The H2O’s offer unsurpassed quality at a VERY affordable price.