Made from high quality, 18/8 food-grade stainless steel, the Classic is safe and toxin-free and doesn"t retain or impart flavors. No matter how many times it is filled, or what is put into it, these Kanteens keep drinks fresh and clean tasting. With a variety of cap and color options, tailoring a Classic to your lifestyle is effortless. The 1.75" mouth opening is easy to drink from and is large enough for ice cubes and bottle brushes (for thorough cleaning). The slim design of the 18 and 27oz size fit in most cup holders and many bike cages.