The big difference that mattered to me between the Hidrate Spark 3 Smart Water Bottle ($60) and the Hidrate Spark Steel is that the Hidrate Spark 3 needs it's batteries replaced after a few months whereas the Hidrate Spark Steel has a rechargeable battery. However, both pretty much have the same capabilities when it comes down to the specifics of the tech. If you prefer stainless steel bottles, colder water, or prefer rechargeable devices, I would go for the Hidrate Spark Steel bottle. Otherwise, save $10 and get the Hidrate Spark 3.