Bumble and Bumble Hairdresser's Invisible Oil Hot Oil Concentrate — Single Dose The powerful Bumble and Bumble Hairdresser's Invisible Oil Hot Oil Concentrate — Single Dose ($8) is a little tube that you submerge in warm water before applying to your hair. It's packed full of castor oil (and six other oils) to leave your hair super hydrated and silky soft. Image Source: sephora.com Bumble and Bumble Hairdresser's Invisible Oil Hot Oil Concentrate — Single $8 from sephora.com Buy Now