Please measure your mug mouth inner diameter size: This lid is suitable for many stainless steel insulated mugs with a inner diameter of 3¼ inches, the most typical is 20 oz Ramblers. If you can patiently spend a little time to measure the INNER DIAMETER of your mug mouth before deciding to buy, it may save you the trouble of returning or exchanging goods because the unfit size. Perfect Fit: Designed specifically for 12 oz coffee mugs with a 3¼ inch diameter, ensuring a snug and secure fit Premium Material: Made from food-grade crystal clear AS plastic that is BPA-free, eco-friendly, and durable, offering a safe choice for your beverages Enhanced Airtight Seal: Features an improved water stop ring for better air tightness, helping to keep your drinks warm or cold for extended periods Convenient Drink Hole: Includes a drink hole that accommodates straws, allowing for easy sipping and the ability to monitor your drink level through the transparent lid Easy Compatibility: Measure your mug's inner diameter before purchasing to ensure compatibility, and enjoy a hassle-free and enjoyable sipping experience