The Oura Ring 4 Sizing Kit allows for you and those around you to find the ideal fit before purchasing. Oura Ring sizes are slightly different from standard ring sizes, so it is important to size yourself using our sizing tools. A properly fitting Oura Ring will result in the highest possible data accuracy, comfort, and overall experience. You can size in store or with an Oura Ring 4 Sizing Kit. With a sizing kit purchase, you will receive a $15 coupon code to use towards your Oura Ring 4 at checkout.