Mobile jammer is a pocket-sized cell phone signal shield that disables nearly all kinds of cell phone signals. It can be discreetly placed out of sight, put in a handbag or pocket.
First of all you should try to google that. Billions of websites will gladly tell you everything you need to know about and there is no need to repeat that all those SEO specialists have already written a billion of times. Also, pay attention to the fact that those jammers are illegal.