From Splenda's website
Like many no and low calorie sweeteners, each serving of SPLENDAŽ No Calorie Sweetener contains a very small amount of common food ingredients, e.g., dextrose and/or maltodextrin, for volume. Because the amount of these ingredients is so small, SPLENDAŽ No Calorie Sweetener still has an insignificant calorie value per serving and meets FDA's standards for "no calorie" sweeteners.