It is recommended that you replace the liner every three months to that your cup is always in the best possible condition. for replacement seal also helps to effectively prevent leaks,so you no longer have to worry about your mug dirty from leaks.Keep your favourite mug with you at all times. Water bottle gasket replacements can deform or wear out over time,resulting in loosening,our for snapseal lid replacement are designed to create a good sealing effect between the lid and the cup,keeping it clean while preventing leaks. For replacement lid is made of high quality silicone, free,safe and ,easy to clean,a must have for everyday use! Just use your fingers to roll off the for replacement parts that needs to be replaced and then slide on the replacement one,easy to complete the operation and make your cup look . Colour:Black Material:Silica gel Package Contents: 4 * Rubber Lid Seals Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.