For small breeds, I recommend the 24" by 36" pen, which will be a great size for an adult small breed dog. (with 1 inch floor grid)
For large breeds, you can choose either the 3' X 3' pen or the largest size which is a 4' X 4' pen. (with 1 inch floor grid.)
Please know I do not make any commission off of these. I sincerely want you to be set up for success after you get home and I highly recommend this product. Also understand by nature, as your puppy matures, they will no longer eliminate in the pen as adult dogs don't go potty where they sleep.
You will also need two Snappy Fit bowls that snap unto the side of the pen. I recommend the 1 quart size. One for water and one for food. You can order these here: