Ryo Double Effector Black Shampoo 543ml Hair Loss Care for Gray Hair - US Seller. Last one PRODUCT SPECIFICATIONS Volume : 543ml Black toning technology ingredients containing black ginseng, black beans, and arrowroot root care for gray hairs. The black coating ingredient sticks to the hair like a magnet and gradually covers the gray hairs darkly. With 2 weeks of use, you will see your gray hair gradually turning brown without extra use of hair dye. Black Toning tm coats hair strands gradually to turn them brown. German dermatology tested and sensitive scalp tested (including 5 hypoallergenic tests) to prove safety for sensitive skins. Enjoy the woody and herbal scent from natural ingredients. Within three weeks, the number of hair loss relief decreased to 73.2%. Patent application Ginseng Root Cell builds up strength so that hair roots can catch hair.