I ordered the 5x5x4 pen for my Lab who was having knee surgery and has to be at rest for 4-6 weeks. Despite shipment from Washington USA to Quebec, Canada it arrived in only 4 days, in time for his surgery. The assembly was easy, The pen is very sturdy, and the nice entrance makes it easy for both he and I to get in and out. It is big enough for him to easily change his position even with an e-cone, and large enough for me to do his physical therapy inside. It's small enough that he won't stay on his feet very much and small enough to fit in the middle of all the action in the house. The only shortcoming, is that there are no inserts for the feet to protect the floor from the feet. Cutting out squares of rubber that was around the house solved this problem. Thank you Aleko