OURA RING SIZING KIT - The Oura Ring Sizing Kit is the ideal way to find the perfect size. It’s a custom sizer that allows for you, and those around you, to find the ideal fit before purchasing. RECEIVE $10 CREDIT - With a sizing kit purchase, receive a $10 Amazon credit towards the future purchase of an Oura Ring. Sizing kit is not returnable (terms and conditions apply). NOT STANDARD SIZING - Oura Ring sizes are different from standard ring sizes, so it is important to size yourself using our sizing kit and to follow the instructions provided. Oura Ring is available in sizes 6-13. There are no half sizes. HOW IT SHOULD FIT - We recommend wearing your ring sizer for at least 24 hours to confirm your best fit. Oura Ring should fit securely and comfortably at the base of your finger. Your ring should not rotate as you go about normal daily tasks. COMFORT AND ACCURACY - A properly fitting Oura Ring will result in the highest data accuracy, comfort, and overall experience. CHOOSE A FINGER - Oura Ring works on all fingers and can be worn on either hand. For optimal accuracy, we recommend wearing your Oura Ring on your index finger. Size the exact finger you plan to wear your Oura Ring on.