The Kallos Cosmetics Biotin Hair Mask for fine and slow-growing hair contains Biotin, which promotes hair growth and at the same time nourishes and hydrates the hair. Effect of the Kallos biotin mask on the hair: it intensely hydrates the hair, rebuilds the structure of damaged hair, fights against split ends, the velvety texture quickly penetrates the hair fibers and leaves a pleasant scent. How to use a hair mask correctly? Apply to washed hair. Leave on for 5 minutes and then rinse thoroughly.