①. Multifunctional RFID Ring: The JAKCOM R4 is a versatile RFID wireless radio frequency ring featuring built-in IC and ID modules to replace access cards, parking cards, membership cards, and other wireless RF cards ②. NFC Integration: With an integrated NFC module, the R4 offers cloud services, including virtual call alerts, location notifications, business card sharing, and note-sharing ③. Simplify Access Control: Conveniently replace traditional access cards with the R4 Smart Ring's IC and ID modules, enhancing security and ease of access ④. Enhanced Connectivity: The NFC capabilities of the R4 enable seamless interaction with various smart devices and services, making it a versatile tool for modern lifestyles ⑤. Stylish and Functional: The JAKCOM R4 offers technology and boasts a sleek and stylish design, making it a fashionable accessory for everyday wear ⑥. Regarding Size Measurement: Use a non-elastic thread to wrap around your finger snugly; slightly tighten the thread; otherwise, the ring size may be too large; straighten the thread, measure the length, and choose the size based on the table below: Standard US Sizes - Size 8: 57mm, Size 9: 60mm, Size 10: 62.8mm, Size 11: 66mm, Size 12: 70mm ⑦. Specifications: Standard US Sizes (Optional) - 8: 57mm, 9: 60mm, 10: 62.8mm, 11: 66mm, 12: 70mm; Carrier Frequency: 13.56MHz, 125KHz; RFID Range: 1~3cm; IC Module Type: UID; ID Module Type: T5577; NFC Module Type: Ntag213; Protection Rating: IP68; Operating Temperature: -50℃ to +80℃; Compatible Systems: iOS, Android; Compatible Platforms: iOS, Android; Materials: Ceramic + Metal; Diameter: About 2.5cm; Powered: No Need ⑧. Package included: 1 x Smart Ring, 1 x English and Chinese Manual, Other items not included