The EPA waiver authorizes sale of E15 only from Sep 15 to May 31 out of a black hose and a yellow hose to flex fuel vehicles only from June 1 to Sep 14. Retailers have shunned building infrastructure due to the costly regulatory requirements which have created a practical barrier to the commercialization of the higher blend. Most fuel stations do not have enough pumps to offer the new blend, few existing pumps are certified to dispense E15, and no dedicated tanks are readily available to store E15. Also, some state and federal regulations would have to change before E15 can be legally sold. The National Association of Convenience Stores, which represents most gasoline retailers, considers the potential for actual E15 demand is small, "because the auto industry is not embracing the fuel and is not adjusting their warranties or recommendations for the fuel type." One possible solution to the infrastructure barriers is the introduction of blender pumps that allow consumers to turn a dial to select the level of ethanol, which would also allow owners of flexible-fuel cars to buy E85 fuel.