Features:1.The smart ring is a fashionable and wearable electronic product with NFC chips.2.It`s able to connect to a smart phone to complete function performing and data sharing, that way many playful and convenient function will be accessible.3.Place the smart ring within the NFC area of a smartphone to perform: screen unlocking, app lock unlocking, app quickly launching, name card and URL information sending and reading, etc.4.You can wear it in all scene such as hiking, running and even swimming, but it`s supposed to be wiped dry to avoid the residual moisture in the ring soak your finger skin for long hour.5.It can be used without any power supply, very convenient.US Size: Circumference Diameter6: 16 50mm7: 17 53mm8: 18 56mm9: 19 60mm10: 20 63mm11: 21 66mm12: 22 69mm13: 23 72mmNotice:Actual color vary from that of the image due to computer settings.Please allow deviations of 1-3mm due to manual measurement.includes:1 x Smart Ring