As hordes of Black Friday shoppers descend on stores in search of deals, many of them are armed with something that has retailers shaking in their boots: smartphones.
AOL's Daily Finance news site reports that about 40 percent of shoppers with smart phones will use them to get a better deal online.
It's part of a trend called showrooming that really took off last year.
Now retailers are fighting back by matching prices and offering free shipping on out-of-stock items.
But with sales from mobile devices expected to double this year, retailers may be fighting a losing battle.
This segment aired on November 23, 2012.