From BruMate’s Website: Made for life on the go, the Resa 35oz combines a 100% leakproof locking lid, built-in silicone swing handle, and our ColdKey™ stainless steel straw for a spill-free sip every time. With a swappable sleeve to protect against dents and dings, and temp retention that keeps your drinks cold for 24+ hours, it’s the ultimate travel companion — plus, most finishes are dishwasher safe for easy cleaning. Resa Tumblers are 100% leakproof with cold beverages and carbonated beverages with ice when in the locked position. Not recommended for use with hot beverages.