Description:   It has both 999 number working mode and advanced working mode, displaying not only numbers but also the letters' A, b, C, D, E, F ', suitable for various occasions. Features: 1. Adopting a new industrial stable chipset 2. Independent storage to avoid data loss 3. Advanced working mode with letter display 4.999 number mode is only for quick use 5. Self checking technology ensures that it can work normally every time 6. Super Error Correction 7. Only address data to avoid duplication 8. Adjustable volume 9. High receiving sensitivity 10. LED tube display, easy to read 11. Beautiful design and portable mobility Specifications: Receiver display host Frequency 433MHz Decoding Learning Code Prompt mode Dingdong/Music/English voice report Display letters as A.B.C. D.E.F Adapter AC 100-240V 50/60Hz, output: DC 9V/1A Working current 600mA Standby current 60mA Size 230 x 160 x 35 millimeters/9 x 6.3 x 1.3 inches Weight 350 grams/0.77 pounds Working mode: Normal mode 1: The screen displays 001-999 and the sound is "ding dong+1-999" Normal mode 2: The screen displays 001-999 and the sound is "call numbers 1-999" Regional mode: Screen displays A01-F99, sound "ding dong+A-F zone+1-99 call" Room mode: Screen displays 001-999, sound "ding dong+room 1-99+1-9 call" Medical mode: The screen displays 001-999 and the sound is "ding dong+room 1-99+emergency call 1-9" Notes: With the development of your business, you can add more transmitter buttons to this system.