1000HOUR™ brush-in gel formula uses a gentle plant extract colour gel. Ideal for more sensitive skin or those who cannot use peroxide-based products, making it a perfect alternative to daily lash and brow makeup application, or expensive brow clinic visits. Dermatologically & Ophthalmologically tested.1000HOUR™ brush-in gel formula uses a gentle plant extract colour gel. Ideal for more sensitive skin or those who cannot use peroxide-based products, making it a perfect alternative to daily lash and brow makeup application, or expensive brow clinic visits.