Made from high quality, 18/8 food-grade stainless steel, the Reflect is safe & toxin-free, & doesn't retain or impart flavors. No matter how many times it is filled, or what is put into it, the Klean Kanteen bottles keep drinks fresh & clean tasting. The 44mm mouth opening is easy to drink from & is large enough for ice cubes & bottle brushes (for extra thorough cleaning).