If you have a trimmer that creates a hard line when fading then the slim line pro li’s are perfect. Used them out the box and started creating my bald lines (Did a high taper) and they do not create any hard lines making my clipper able to take the line out easily without a struggle. They are perfect for that very purpose.
Would have been a great trimmer but can pull hair. You must oil everytime you use it to avoid pulling. Other than that its a great trimmer, excellent for travel and great print design.