The lever on hair clippers (often called the taper lever or blade adjustment lever) serves a precise function essential for professional haircuts. Below is a practical breakdown:

1. Core Purpose: Adjusts Cutting Length Instantly
Shortens hair when pushed down (↓): Blades move closer together, cutting hair closer to the scalp. Used for tight fades or sharp edges.
Lengthens hair when pushed up (↑): Blades spread apart, leaving hair longer. Ideal for blending or adding texture.

2. Key Uses in Haircutting
Seamless Fading: Start with the lever down at the neckline for the shortest cut. Gradually push it up as you move toward the crown to create a smooth gradient.
Blending Guard Lines: Soften harsh transitions between guard lengths (e.g., where a #1 guard meets a #3).
Detailing Hairlines: Use lever down for crisp edges around ears/neck; lever up for softer, natural finishes.

3. Practical Technique
Direction Matters:
Lever DOWN: Cut against hair growth for maximum shortness (e.g., nape/back of head).
Lever UP: Cut with hair growth for subtle texture (e.g., top/crown).
Dynamic Adjustments: Slide the lever mid-stroke to thin bulky areas (e.g., dense crown hair) without changing guards.

4. Lever Positions Simplified