The body of microcrystalline zirconium , the whole body of R4 is made of microcrystalline zirconium , with refractive and dispersion performance, so that the whole emits a unique round . The designed circuit structure greatly reduces the electric field interference between the modules. Compared with the previous generation products, it has increased the sending and receiving distance by 3 and is compatible with card . From 125KH to 13.56MHz frequency band, R4 can a of standard encrypted C card or D card, helping you effectively deal with card swiping scenarios in all fields. Suitable for with a circumference of 62.8 mm R4 is a multi-functional RFID wireless radio frequency ring. The built-in IC and ID modules can be used to replace radio frequency cards such as access cards, parking cards, membership cards, consumer cards, etc.; the built-in NFC module can be used to implement virtual incoming calls, location notifications, cloud such as business card sharing and memo sharing. Applicable people: children Wearing style: wrist strap Applicable system: iOS, Android Compatible platforms: iOS, Android Colour: black Material: ceramic + metal Size: Diameter: about 2.5cm Package Contents: 1 x Smart ring Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.