I bought the wizdog because I had heard some good things about it, but it's not worth it at all. It's perfect if you use newspapers because it's the size of an unfolded newspaper, but pee pads don't fit in it properly and you have to use at least two. The little grate that goes in it is also a piece of junk. It doesn't fit well in the frame and Tuffy was able to pick it up and run around with it.
I don't recommend it at all. I use Simple Solution's pee pads that I get online at kingwholesale.com They work great, very absorbant. I use a Simple Solution's frame for the pads also.