Our silicone cover is designed for protecting Oura Ring Gen 3/4 and ringconn, elastic material made to fit all ring size. Fits All: This elastic case is compatible with all size, please pick the S for ring size 6 7 8 9 10, M for ring size 11 12 13, and 14 15 from Gen 4. Great Protection: The sleeve covers the smart ring fully, essential for protecting your smart pal during physical activities including working out, lifting weights, sporting events or anytime when you may push hard with fingers. Easy to Use: The case is slim and strechy, easy to slide on the smart ring, adds the least thickness to the ring but get the most protection. Service: For any quality issues, please contact us for replacement anytime. Designed by Newjourney, made by BandSmith. Silicone Case for Oura Ring Works with Oura Ring Gen 4 and 3 Soft and flexible silicone made for all around protection Easy to install and replace Size Chart S works with Oura Ring Size 6/7/8/9/10 (does not work with the 4/5 from Gen 4) M works with Oura Ring Size 11/12/13 and 14/15 In the Package Silicone Skin for Smart Ring