жидкость серии мел

The advantage of the liquid chalk dustless teaching series: 1) Works like a Marker Dries like chalk ,4 colors(white,yellow,red,blue) you can choose,colors also can according to the customers’ requirements. 2) They offer an innovative alternative to traditional chalk .they work on any smooth surface.no dust,no toxic.they earily wash off any non-porous surface. 3) Can be recycle use for perfusing ink repetely,so compared with ordinary chalk and board marker,more cost-saving.