The Wire Mesh Top will fit any of Midwest's exercise play pens, when the exercise pens are placed in a square configuration. The Wire Mesh Top is secured to the exercise pen with 8 Metal Bolt Snaps (included). The Wire Mesh Top is made with strong 9 and 11 Gauge Metal and is Gold Zinc Plated to make it long lasting. The edges are contoured to 90 degrees for a secure fit, and has a 1 1/2 inch spacing.