I have a coarse heavy beard, I have tried more then 45 razors in my collection from 3/8 to 8/8 and from full, extra and quarter hollow. The only razors that give me a close, clean and smooth shave are the 7/8 and 8/8 quarter hollow. They are not flexible, singing or vibrating blades. If you have a light thin hair beard you can use and shave with all the razors available in the market. The singing or flexible blades in a coarse heavy beard will cut the hair and the skin spaced between the hair. Bleeding is the result. Quarter hollow only cut the hair and not the skin, since it does not flex it stays in the course you set. Other members will have their opinion, but this has been my experience with my razors and my beard. Thanks Juan.