Ordered the HTC Hair Trimmer Model AT-528A on TEMU and upon arrival noticed that the attachements only go up to 7 mm in lenght. Since I dont want a buzz cut I needed to design some of my own. Through trial and error I found out that 30 mm is the ideal lenght of my hair and 15 mm for the sides and back contrast nicely. Took a few iterations to figure out how the hair flows ideally toward the blade.