Klean Kanteen Wide (w/Stainless Loop Cap) Durable and High Quality Food Grade 18/8 Stainless Steel Construction Comes with BPA-free Polypropylene #5 cap with Stainless Steel bottom to create an all-stainless interior Large 2.125 inch (54 millimeter) opening fits ice, easy to fill and pour; Compatible with all Klean Kanteen Wide caps Easy to clean electropolished interior doesn't retain or impart flavors Backed by the Klean Kanteen Strong as Steel Guarantee