These quick connectors seemed like a great idea. No more screwdrivers needed to plug and unplug various wires. But the execution of the idea is far from perfect. I imagined they must have a spring inside to keep the metal sheet coming back over and over again. They don't have any springs. Once you push in a thick wire, the metal sheet gets bent and inserting a thinner wire will no longer result in a secure connection as there is less push from the bent metal. Second, I would have thought that the part effectively pushing the wires is flat at the end. It is not flat at the end, it meets the wire at a 45 degree angle, making the "connection" very loose. The wire can wiggle left and right and can eventually get loose. Great idea, poor execution.