What are output barrier strips?

If you think you're not familiar with barrier strips, you've probably seen one and not realized it. It's a long block of plastic which holds a number of screw terminals, each one sparated from the next by a low "wall" or barrier. They were standard on amps during the fifties and sixties.

The barriers tend to be set very close to the screws and the screws are close together too, so the best connector is a small spade or nothing at all.