QO and QOB Circuit Breakers have one, two and three pole thermal magnetic circuit breakers provide overcurrent protection and switching on ac and dc systems. They are designed to meet residential, commercial, and industrial requirements to protect electrical systems, equipment, and people. This circuit breaker accessory allows for adjecent single poles to be combined so that when one branch trips, equipment on the secondary circuits can be protected simultaneously. This products is certified to adhere to the specifications listed in the data sheet by UL. This product is a fixed attachment.