What on earth is a silver lab??

My uncle is looking for a labrador, as his beloved hunting companion, Vegas ped away several months ago, and he's like to get back into training and hunting and such with a new puppy. Vegas was a black lab, but he'd like to get a chocolate like my grandpa's hunting lab, Hershey. I've been doing some research for him online and came across numerous breeders trying to sell ?silver? labs!!! I didn't even know they existed!