With all the street smarts you need for the daily grind and a hidden adventurous spirit, the Stainless Wide Flip D-Ring effortlessly transforms from a flat, low-profile cap to a sporty, functional loop cap you can clip on to just about anything. The cap is made from BPA-free polypropylene (pp#5), but the inside is 18/8 food-grade stainless steel, so your drinks never touch plastic. With just one rugged moving part, it's designed to be durable and is made to last.