I tried this (30mm) and the same in 45 mm. I tested the products on my daughter with straight, long hair and myself with shoulder-length, curly hair. I find that 30 mm works best for my hair and 45 mm for longer hair. My hair can get frizzy quickly, but this product calmed it down nicely. My daughter's hair also felt fresher. I don't have much practice using such styling tools, and I found it a bit difficult to achieve the desired result. I will continue to practice. I like that the product has a long cord, is gentle on the hair, and is reasonably priced. #HBONORDICA #BJÖRNAXEN #STYLINGTOOL #LYKOINFLUTESTER