This was almost unusable. I tried to use the simple screw connectors. Something you take for granted in the past. The bottom of the screw heads are usually textured to get a good grip on the wires. These are polished and slightly thicker in the middle forcing the wires to the outside when you tighten them. There should be a barrier on the outside that holds the wire in place under the screw heads. This switch has only one barrier on one side and is spaced so that the wire escapes when the screw is tightened. I was using 12 gauge wire (single strand).
I found the switch useless. A low price is nice, but only if the switch works. Pay more, get a switch that works. This one will waste your time as it did mine, until you believe it is not going to work. I'm an electrical engineer. I've installed hundreds of switches. This is the first one I have found that is so low in quality that I can't make it work.