Vietnamese Keyboard Stickers - Labels - Overlays with White Characters for Black Computer Keyboard The Overlay adhesive firmly attaches the overlay in place without damaging the keyboard key or the original key legend. The adhesive will not ooze, harden or wear out. These keyboard stickers are transparent with the character set displayed in a unoccupied corner of each key. The existing letters on your keyboard show through the sticker. High Quality. Overlays are manufactured of durable Lexan. They won't tear, crack, discolor, or slip off even after years of use.