The Ba Gua (or Pa Kua) consists of eight sacred emblems sometimes called trigrams, directions or activities. It is used to encourage the flow of Chi (life force) which is regarded as the primary building brick of the Universe.
The Ba Gua is said to have been born on the back of a creature that rose from the deep at the dawn of time. The secrets of the universe are believed to be contained within. The Ba Gua is used in Feng Shui to balance and move Chi. The Ba Gua not only expands chi, but also strengthens and draws in auspicious chi.
A powerful device, this Ba Gua is used to deflect shar qi (negative energies) caused by Feng Shui errors. Also, it adjusts and nullifies the malevolent chi directed at the house/office, from outside forces. The Bagua is also used for houses suffering from the T-junction sha or nearby cemeteries.
Ba Guas with Concave Mirrors turn the objects they reflect, on their head. They are used to deflect telephone poles, electrical poles, electrical transformers, high rise buildings, large plants/trees or mountains and to turn around a street curving away from you.
Ba Guas with Convex Mirrors are usually used to pull energy towards you when your door doesn't face the street and in places where large families live (Apartment Buildings)/large level of employees work (Factories)/heavy energy drains happen (Hospitals) - to keep the good chi from flushing out.
When in doubt, Ba Guas with Plain Mirrors can be used.
Ba Guas made of Rubber, Plastic, Thermocoal or Paper Board should never be used. The best ones are Ba Guas made of Wood or Metal.
The Ba Gua should never be used indoors. It can be hung over the main door, the back door and windows on the outside.