Widely Applicable: It is suitable with standard ceramic cup mouths, smooth glass cup mouths, stainless steel vacuum mugs, and sports plastic water cups. It achieves airtight adhesion by the adsorption property of silicone, providing dust-proof and spilling-proof effects while enhancing heat preservation. Easy to Use: Completely dry the edge of the cup (moisture will reduce the adhesion), then cover it and gently press it to create a vacuum with the edge of the cup, and it will be adsorbed Note: Measure the inner ring of your cup to ensure that the lid can fully cover the cup mouth (flat cup mouth). Heat limit: Do not place in a microwave/oven with a temperature higher than 260°C. When filling hot drinks, do not lift the lid directly (the adsorption force reduces when exposed to steam, which may cause it to fall off and get scalded). Feature: Silicone material, dust-proof, sealed and leak-proof, with good adsorption, can closely fit the cup mouth and will not leak when poured. The material is lightweight, flexible, and won't break even after repeated tearing. High-temperature resistant, -40 °C to 260°C, Stain-resistant, fingerprint proof.