The Rabbit Haven provides the following:
"Portable wire exercise pens are the most versatile, the easiest to clean, and the best way to give your rabbit what they need. Space, toys and a clean environment of their own while living inside with you! For those who want a quick housing solution without spending a lot of time and money, the wire pen arrangement (X-pens also called puppy corrals) gives you the best housing for your money and helps the rabbit feel at home in their own space. Exercise pens allow for the bunny to see what is going on around them. This gives a feeling of knowing what's happening and of being included in the household activities.