A needle stroke length of 3.5mm is the versatile range and can execute clean, crisp lines while still managing delicate shading and soft color packing. It's a recommended starting point for beginners seeking an all-purpose liner. However, a longer stroke length of 4.0+mm is typically only used for lining, as it packs in tattoo ink with hard-hitting. The extended stroke allows the machine to drive the needle more aggressively into the skin, laying down extremely saturated, hard-hitting lines. But this power comes at the expense of finesse and control.