The USED Square D QO3100 3 Pole 100 Amp Circuit Breaker is a plug-in mounted miniature circuit breaker with a screw mounting style. It has an instantaneous break time and a maximum amperage of 100 A, rated for 120/240 Vac. This model is designed for industrial use, providing reliable protection for electrical circuits with a current rating of 91-100 A. The Square D brand is well-known for quality electrical equipment and supplies, making this circuit breaker a dependable choice for various applications.