Specifications;   1. Can work with 500pcs multi-key transmitter in max 2. Can show 3 group call number at a time 3. Show 4-digit number from 0001-9999 and first letter can be A-Z 4. Can indicate different service type via words or letter. ( call; bill; drink; dessert; help etc and A-Z) 5. Can record when the call come in and count the call times of each number 6. Can track the history calls by up and down 7. Shows current time when stand-by 8. 3 reminder ways: sound prompt and vibration or both 9. Battery is rechargeable: 3.7V Lithuim battery 10.Dimension: 50*51*16mm

11. Color: Black

12. Output: DC5V–1A