My convection plate works well. The grates got a lot tighter and barely fit, but they do fit.
I didn't have a great experience with Horizon. Emails weren't answered so I had to call. They were good on the phone and I got mine ordered. I called two weeks later because it hadn't arrived yet and they "couldn't find any information or order" for me in their system or anywhere. It was like my first call never happened. I had to start from scratch in ordering the plate and a charcoal grate.
I did get them finally and they work great, but it shouldn't be so hard to do business with someone.