Two Way Holder or Twin bulb holders

These are twin holder or two way holder. As the words suggests, they are used with two bulbs. It has a string. You pull once it lights one bulb, pull again, it lights another one, pull a third time, it lights both, and the forth time it will put both bulbs off. So the string can act as a switch despite having your normal house light switch. You can get from 1 to 3 pcs