Gizmo has recently figured out how to get the pads out again from the pad holder, so I purchased this one last night
Amazon.com: Rascal Dog Litter Box PIDDLE PAD... , I'm hoping it will hold better than the one I have currently. I also got him a new playpen by richell, it's all wood framed and really nice, with 2 different doors, I ordered the medium sized one, its really nice because it has a top that clips onto it if you leave him alone, so he can't climb out.
I really liked this potty pad/ litter box because it has the holder as well as it being 3 sided, so he will feel like he has privacy, plus if he decided to lift his leg in the future, the 9" sides would contain it. It's a little pricy but I figured if it helps, it will be worth it, and it had great reviews :-) it also has the option of using the pads, or the artificial turf, as it has a reservoir in the bottom as well. I am going to try with pads though and hope he can't get them out of this one haha. He's like a little Houdini when it comes to removing pads :-( I will et you all know how this one works when I get it :-)