3 inch clear plastic pot. With side slots. Precise measurements: this pot it is 3 inches at the top, 3 inches tall, and tapers down to a 2.25 inch base.
It is made of light weight, 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. Phragmepedium, Paphiopedilums, being ground dwelling terrestrial orchids, should have opaque pots.