When purchasing Piano Hair, the most critical technical factor is the Hair Grade (e.g., 10A, 12A) and the Material Source. You should prioritize 100% Remy Human Hair, which ensures the cuticles are intact and aligned, preventing tangling. Additionally, verify the Color Ratio consistency; high-quality piano hair requires a precise 50/50 or 30/70 blend of two contrasting shades without bleeding or blurred transitions. Ensure the Weight per Bundle is standardized (typically 100g) and the Double Weft technique is used to minimize shedding.