The NAYAD® Genesis 40 oz Stainless Steel Double-Wall Mug features an innovative foldable handle for compact storage and portability. Crafted with rust-free 18/304 stainless steel and a powder-coated matte finish, its heavy-duty 4 mm inner and 5 mm outer walls offer exceptional durability. Double-wall and copper-lined insulation keep beverages cold for 10 hours. Includes spill-proof dual-function and straw lids, and car cup holder compatibility. FDA certified.