I actually bought three of these for my 5-1/2 lb. Yorkshire Terrier.....all different sizes.  I bought them when she was a puppy.   I hope I'm rating the right one.  This one has a removeable, water-proof bottom; the other two I bought the bottom did not come off and were not water-proof.  The water-proof bottom is great but she tried to get under the bottom where it was attached with Velcro and I was afraid she would get squashed...she was only about 2 lbs.  She is a real pistol!!   I think these Pet Pens are great and Wayfair has the very best prices.