marketing funnel theory: It's Not as Difficult as You Think

http://www.colegiosentli.edu.mx/portal/index.php/forum/user/275288-s6ztnlb996

A funnel is a tube or pipe which is vast at the best and narrow at the bottom, useful for guiding liquid or powder into a little opening. Funnels are generally made of stainless-steel, aluminium, glass, or plastic.