The Flash comes with 2 extra fists, 3 pairs for speed force effects and a figure stand. Some of the effects are easy to replace like the ones near the ears. A few replace part of the forearms that hold on the elbow. What is tricky is finding the clips near the waist as they are not the most obvious tabs to find.
DC Variants in the Play Arts Kai series has always been interesting to see and the Flash doesn't fall far behind awesomeness. I couldn’t think any more parts that should be included in the set, which means that what you need is all in one box. What is quite weird is only the almost impossible to achieve waistline but that is all that I could only ramble.