Made entirely of durable silicone. the 450mL Silicone Lid is a cover designed to transform the Ti-Double H450 Stacking Mug. Ti-Single 450 Cup. Ti-Double 450 Mug. and the Stainless Vacuum-Insulated Mug in 450ml into travel-safe beverage containers and protects from dust and debris.  The snug fit secures easily onto the top of the drinkware with an open lip for drinking and insulating hot and cold beverages.