The Ultimate Exercise Pen is the toughest on the market and a wise investment for serious professionals and pet enthusiasts. It folds directly into itself, taking up minimal space, consuming less time in the set-up and take-down processes. The removable drop pin allows your pen to be easily joined with other pens or to your crate for extra play space. For added convenience, the pen includes a 3-point locking door on all sizes and an easy carry handle for transporting. For your pet's safety, the Ultimate Exercise Pen has no exposed screws, wires or pins to injure your pet. The pen includes eight 2'-wide panels totaling 16 feet in length. All pens have a zinc electroplate finish, added after welding, to reinforce protection.