FIT Top Replacement Filter Pucks, 2-Pack FIT Top is the only system that filters water as you fill the bottle instead of forcing water through a filter as you drink Save hundreds of plastic water bottles and drink cleaner water with the convenience of a FIT Bottle The only BPA-free filtering bottle allowing use of drink additives Filter Isolation Technology (FIT) preserves and protects the filter from whatever you are drinking Replaceable filters, compatibility, fits hands and holders and no more fighting with straws for a drink