... projector, glass plane, table top, wall and other smooth surfaces.Display screen: 20 inch - 100 inchWorking condition: temperature: -4oC - 40oC, ... writing pen can be used for writing on any screen in a traceless manner, realizing dust-free writing.Stroke ... , compasses, rectilinear scale,etc.Support functions of soft keyboard,screen, flashlight, etc.Support functions of pencil,brush pen, combination ...