Compatibility: Specially designed for Hydro Flask Press-In Straw Tumbler Lid. Fits snugly on 0.35–0.4 inch (9–10mm) straws to help block dust and keep your drink cleaner Safe & Soft Silicone: Made from food-grade silicone. Odorless, flexible, and durable—safe for all ages without cracking or deformation over time Dust Protection On the Go: Our straw stoppers can effectively blocks dust, dirt, and small insects from entering, ensuring a clean drinking experience with the straw, whether in the gym, office, or camping site Effortless Maintenance: Dishwasher-safe reusable stoppers remove easily for cleaning. Washes like new for long-term use with no residue or wear Colorful & Personalized: Features 8 fun straw covers in vibrant colors to match your tumbler style—ideal for home, office, outdoor use, or as small thoughtful gifts Designed for active lifestyles, these 10mm dust-proof stoppers create a hygienic seal - ideal for gym bags, car cup holders, and outdoor adventures. Key Advantages: Precision Fit - Engineered for HydroFlask's 20oz, 24oz, 28oz, 32oz and 40oz tumblers with press-in straws Advanced Protection- 0.4" thick silicone barrier blocks dust, insects Multi-Pack Value - 8 colorful covers Quality Material - Food-grade silicone, dishwasher safe