Four Paws K-9 Keeper Exercise Pen have 8 panels, 24" in width. The exercise pens are available in heights of 18, 24, 30, 36, 42 and 48 inches. Our patented, inter-locking system securely holds the panels in place and assures the safety of pets. K-9 Keeper Exercise Pens feature a full convenient door with security latches for easy walk-through access. K-9 Keeper Exercise Pens can be configured in many different positions. All K-9 Keeper Exercise Pens fold flat for easy storage and portability.