The straight-sided bottles looked just like any other soda pop.  In addition, imitators almost universally adopted the same diamond shaped labels that Coca-Cola had on there bottles.  Coca-Cola needed unique bottle which required no paper label at all.  "We are not building Coca-Cola for today.  We are building Coca-Cola forever.  It is our hope that Coca-Cola will remain the National drink to the end of time".