green board/chalk boarb/dry erase board:

1.It is the best among the writing boards

2.The hardness of the surface is up to 6.5.It is formed while porcelain and thin steel sheet are combined when fusing at a temperature of 800 degree celsius.as a result,it is scratch-resistance and damage-resistance.and never fade.

3.Other types of frames can be also used for porcelain board.

4.Various sizes are available.