GAYAS HERBAL HAIR DARKENING GEL is formulated using patented UK technology with over 10 years of scientific research, It is specially infused with Aloe Vera, Olive, and Ginseng Extract which actively treat and nourish hair roots for a strong and healthy hair. It is an ammonia-free product and contains a non â toxic substance which darkens your hair quickly giving a long-lasting natural black hair. Read and follow the instructions carefully. Do not use the product if you have Rash on your face.