This one is ZJ-46 mini version with clock function. It can pair up to 999 wireless calling buttons and 3 manager controller.
This display has 4 digits/letters, each one can be set 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, b, C, d, E, F, H, J, L, P, t, U. It can combine numbers, words, or num+letter.
The wireless calling system has millions of different code which can be paired easily and freely. And it is widely used in restaurant, café, bar, tea shop, KTV, bank, office, factory, hotel, hospital and so on