Extra Dark, as the name implies, has high Ash Content. It is thick and rich and is the most effective Oil for all your Hair and Skin conditions. Sunny Isle Extra Dark Jamaican Black Castor Oil s processed the traditional way. Organic castor seeds are roasted and ground by a manual Grinder and then the crushed beans are boiled to extract the 100% pure, dark brown, organic oil. It's the best quality oil on the market. Why you may ask? Compared to other brands it is the darkest Jamaican Black Castor Oil because the beans are roasted longer which produces more Ash Content. More ash content increases the effectiveness of the oil. Therefore the Sunny Isle brand will strengthen and increase the length of your hair faster than any other brands on the market today.