At 18 high the walk-over exercise pen can keep small dogs and older dogs safely confined to a roaming area of up 14sq feet. Four paws exercise pens are gold zinc plated for maximum durability. All pens have eight (8) panels which are 24 in width. Our patented, inter-locking system securely holds the panelsin place and assures the safety of pets. K-9 keeper exercise pens feature a full convenient door withsecurity latches for easy walk-through access. 18 INCH HIGH