When I first opened it I was skeptical, thinking it looked like snake oil.  I installed it according to the directions anyway, hoping against my better judgement that it would actually work as advertised.  I installed it on a telephone pole with the small antenna in the corner of my living room, in an area where I generally have no signal or 1 bar maximum.  Now I have 4-5 bars throughout my (small) house, and can make rock solid calls where before it was impossible.