The eight inch pot is 8.25 inches wide with a half inch rim making the opening 7.25 inches. The height is 8 inches and the base is 6 inches.
It is made of sturdy, translucent plastic that allows light to get to your orchid's roots. This is very helpful for most epiphytic orchids that are used to having their roots exposed in their native habitat (in trees). This would include Phalaenopsis, Cattleya, Dendrobium and many others.