When it comes to nail structure, most people focus on the apex — but one of the most critical (and often overlooked) elements is the lower parallel. If your lower parallels are incorrect, no amount of apex work will truly fix the structure. They are the foundation that everything else relies on. Let's break down why they matter. 1. Structural Strength This is the most important function of lower parallels. Lower parallels create a straight, supportive sidewall that runs from