Only Fits the 20 oz Tumbler & Lowball. Does not fit the RTIC 30 Oz Tumbler.;Rough riding in the boat, off roading in your truck, ATV or in the field; the sliding closure resists spills and is straw friendly.;The RTIC Lid is crystal clear and BPA free.;Splash Proof Sliding Lid;Reduces the amount of spillage if your tumbler was to turn over