A good bagua mirror is in octagonal shape, usually framed in wood and measures about 4 to 6 inches across. It has the eight trigrams marked around the outside with a round mirror in the center. The bagua mirror is easy to use and inexpensive protection method for “shar chi” or poison arrows. The bagua mirror is used massively in “Form School of Feng Shui”, which was the first and oldest feng shui school dating back to Song Dynasty (AD960-1279). Form School of Feng Shui which is the basis of all schools of feng shui overides other school of thoughts when certain shapes and formation in an environment is not in a desirable mode. Since most of us live in urban areas, the natural elements of landscape and formation are represented by buildings, roadways and other manmade structures.