I use the Top hat adapter on my rat. It fits perfectly, I raced this setup at the last ‘Willow’ So.Cal race event and it performed flawlessly, which gave me the win in 2 classes. I will be running the same setup on Oct.22 at the Grange. Buy it, you will not be disappointed. The only thing you need to consider is what size sprocket and Disc to use so they don’t interfere with each other. Check my post in the Rat Rod section, it’s all in there.