It is best to place the Feng Shui concave bagua mirror when advised by a professional feng shui consultant. Traditionally, the Feng Shui bagua mirror is placed above the front door or above a big window that is facing questionable outside energies. The purpose of a concave mirror is to minimize/absorb negative energy.
Bagua Mirrors are used to activate, enhance and circulate Chi, to deflect negative energy and amplify the light in small dark areas. The concave bagua mirror is a round concave mirror 4 inches diameter, set in an octagonal wooden frame painted yellow, with the eight trigrams in yellow, black and red.