HEALTHY MATERIAL: Made of food grade silicone. Durable, non-toxic, reusable and safe. LENGTH: Widest – 4.92 Narrowest – 4.13 TEMPERATURE TOLERANCE: -4??F – 284??F SUITABLE: Fits mug/glass/cup which diameter less than 3.94 DUSTPROOF: Our Cup lids will keep your cup clean and prevent your drinking form all dust and debris in the atmosphere.