Eight HDPE panels, each 21 in wide and 31.5 in tall, connect into whatever shape a room allows - a square pen in a corner, a long run along a wall, or a barrier across an opening. A 14.5 x 30.5 in door saves stepping over the top every time. HDPE stays smooth rather than scratching, and wipes down after a muddy afternoon outside. The set weighs 20.5 lbs assembled. It works on a floor indoors or on grass. Black, with white as the alternative. Assembly is required and no tools are needed.