4 inch Square Black Pot

The plastic pot is 4 inch (10.1cm) wide (diagonally) at the top, 3.75 inches (9.5 cm) tall.  The base tapers to 2.5 inches (6.4 cm) wide.  The advantage of a square pot is that you can pack more together than round ones.  

It is made of sturdy, black plastic that are ideal for terrestrial plants such as Paphiopedilum and Phragmepedium.