1. Efficient whitening brush head with SGS international certification for efficient teeth whitening 2. Crescent shaped brush head, fits the tooth shape, cares for gums, and is clean and efficient 3. Moderate softness and hardness of brush bristles, synergistically exerting force 4. Adopting copper free hair planting technology, safe and hygienic 5. Snap-in design, easy to install 6. Size: 84x18.3mm 7. Applicable to T501/T501C electric toothbrush