Waterproof - LANOU waterproof sensor covers for libre 3 is much smaller and suitable than the normal one to help you feel free in swimming,shower and any other water activities. No glue on the center - The adhesive patch specially designed with no hole and no glue on the center,if you need change the patch it will not tear your sensor off.Long lasting - Comfortable and durable materials make the overpatch last 14 days and do not effect sensors date reading. EASY TO STICK - Just tear off the backing paper you can use the sensor covers easily.package contents: 10/20/30/50/100pcs sensor covers