As part of its rebranding from H20 to X-1, it expanded its “waterproof” product concept to its “waterproof, weatherproof, and sweatproof concept”. In doing so X-1 added sweatproof headphones, waterproof headphones and headphones for women to its existing waterproof cases/armband products. Collectively, these products represent X-1’s __________.
Product class
Product form
Product utility
Product mix
Product item