Whispering Windows More Hummingbirds Is A Decorative Way To Reduce Birds Crashing Into Your Windows. White static cling designs put on the inside of windows help break up the reflections so birds can see the glass and not crash into it. Clings to the glass. Can be removed, cleaned and reused. Contains two each of four white designs. Decal sizes are 4" x 4" and 4" x 6". Specifiy hummingbirds or chickadee.