i believe they are signle, i found them in another friends garage when we were cleaning it we snatched them to put in his truck and i have taken them out to look at them, i know they work cuz i hooked them up in my truck. the amp does not go into protect mode it stays on, and the subs are bridged together on the outside of the box on the terminals, i just ran wires from the positive and negative on one terminal to the other and then ran the positive and negative from the amp to one terminal, and the gains were set half way but when i wasnt gettin any sound i turned them up to see what happened and i got nothin...