VieBeauti Teeth Whitening Pen kit.  It includes four whitening pens and one desensitizing gel pen, totaling \(5\times 2\) mL of product.  The formula is enamel-safe and designed to remove years of stains while relieving tooth sensitivity.  The active ingredient is carbamide peroxide, which is effective yet gentle for sensitive teeth.  The compact, travel-friendly design allows for easy application anywhere