The WIP helmet seem to fit my l-xl head well. Had a ProWIP helmet that i lost and decided on the Pro Wiflex as the replacement (the cheaper Wiflex looks to be almost the same - no ear flaps and no magnetic buckle). Pros: the wiflex is super-light. I think i have less whiplash when crashing because of the light weight. The ear pieces on the Pro version are nice extra protection. The size adjustment that lets the whole shell expand is a neat concept and seems to work well. Cons: the shell feels like polyester. I will need to be careful not throwing it around. It is not a hard shell.