They are also called Bagua/Bagwa mirrors, they are octagonal in shape, made of wood and usually about 4 to 6 inches across. They have eight trigrams marked around the outside with a round mirror in the center. A concave mirror in the center deflects shar chi away at an angle instead of back at the object so as not to be at war with the object. I'm not quite sure but I think a convex mirror brings the energy into you. Think it might be used for sucking in sheng chi. I think the mirrors are supposed to be placed on the outside of doors or windows. Not on the inside. So you could place the mirror on the outside of a window that faces your neighbor.
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