Cover up to 50% gray hair with Clairol professional beautiful collection of advanced gray solution semi-permanent hair color. No ammonia no peroxide and gentle enough to be used right after. With advanced o2 technology. With no ammonia or peroxide and by replacing ammonia with natural oxygen this gentle semi-permanent hair color can last for up to twelve washes. Also all shades cover up to 50% gray effectively for up to twelve shampoos.