The Square D by Schneider Electric QO 100 Amp Two-Pole Circuit Breaker is intended for overload and short-circuit protection of your electrical system. When a QO Visi-Trip circuit breaker trips, the handle snaps to a midpoint position between "OFF" and "ON" and a highly visible, red indicator easily identifies the tripped breaker. Plug-on design, easy to install. Compatible with QO load centers, CSED's and NQOD panel boards. Allows up to 120/240 VAC. Allows up to 10,000 AIR. ANSI certified and UL listed