1). 4mm Heat Tempered Glass 2). Paint film: smooth, no reflection, no dot with Diameter greater than 0.3 mm. 3). Magnetism: absorption of more than ten pages of A4 paper 4). Scratch: No Chromatic aberration, no scratch in the surface of our GLASS WHITEBOARD. No grey, black or any dot with Diameter greater than 0.3 mm in the surface of our Glass Whiteboard. 1).It is a full tempered safe glass,if it is broken,it will spit it to small piece. 2).It is 7 times harder than float glass 3).It is corrosion-resistant,and could be used more time than of the ordinary board. 4).It is easy to clean,Simply wipe with a eraser,a dry cloth or normal window cleaner. 5).It has polyurethane adhesive which is eco-friendly,non-toxic and has excellent adhesion. 6).It has glass baking paint which does not contain toxic subsatances toluene and xylene