Strefa czasowa -10 and other 85,000 icons from Icons8 icon pack follow the visual guidelines of the operating systems: Windows, iOS, Android KitKat, and Material. PNG format is free up to 100x100 px. Icons are availble for download in PNG and vector (SVG, PDF, EPS, and more).
A timezone -10 icon is represented with a foldout map icon. The map will have straight sides, but on the top and bottom will be a zig zag pattern to show it's foldout component. An important part of the timezone -10 icon is that there will circle and inside the circle there is a -10.