The medium pen is our most popular size in the 27” height. It provides a generous space and can be set up in two different configurations, a square (2 panels by 2 panels) or a rectangle (1 panel x 3 panels). We recommend the medium for most customers as it provides the perfect amount of space and can easily be expanded if needed. The Medium 27” Lucidium Dog Pen is an oversized, indoor enclosure, with 3 color choices, a drop-down bar at the door for walk-in access, and clear acrylic panels. All Lucidium pens are intended for small and medium breed dogs (up to 40 lbs.), puppies, and other small animals like rabbits, guinea pigs, kittens, and ferrets. They are not designed for large dog breeds or pets that are aggressively trying to escape. Size: Height: 27" Width x Length: 48" x 48" or 24" x 72" (Can be assembled either way) Approximate weight assembled: 40 lbs.