The second advantage is differentiation. A firm differentiates itself from its competitors if it can be unique at something that is valuable to buyers (Day 1994). The sustainability of differentiation depends on two things, its continued perceived value to buyers and the lack of
competitor ability to imitate. Again, Porter defines a driver of sustainability that is logistics related. The driver entitled, "The sources of differentiation are multiple," is defined as, "The sustainability of a differentiation strategy is usually greatest if differentiation stems from multiple sources, rather than resting on a single factor such as product design" (p. 159).