Nothing tastes quite like crisp clean water fresh from a river or stream. But to be safe you still need to filter it to remove particles, protozoa and bacteria like Giardia, salmonella and cryptosporidium. If you prefer the design of the Klean Kanteen ? Classic bottles but still want to take your Klean Kanteen? on the trail, just pick up one of these small, light weight water filter adapters. One end screws into the classic bottle and the other end has a universal thread design that connects to most standard backcountry water filters.Fill up your Klean Kanteen? with cool water straight from the source.Lightweight and durable. Universal thread design compatible with most standard backcountry water filters. Interchangeable between all Klean Kanteen classic bottle sizes. No BPA, phthalates, lead or other toxins. Dishwasher safe. Materials: Polypropylene (pp#5) Size: H 2.25"x W 3" Weight:1.5 oz.