The octagon pet pen is a wonderful place for your small dog or cat. Great training aid for your new puppy! It is vented on all sides and the top can be left open or closed. The front door allows for easy access when opened. It is a great travel pen and easy to set up and take down for quick access. *Small: Capacity 30 lbs Measures Approx. 29 L x 29 W x 17 H Medium: Capacity 60 lbs Measures Approx. 36 L x 36 W x 23 H Large: Capacity 90 lbs Measures Approx. 46 L x 46 W x 28 H.