The Square D by Schneider Electric brand safety switch is designed to be rugged and reliable, providing exceptional performance in the harshest conditions. General purpose safety switches are designed for commercial, institutional, industrial and manufacturing facilities. F Series 100-200A safety switch electrical interlocks are available in kits for field installation. Each kit includes instructions for proper field installation. A swing arm is actuated by the switch mechanism, breaking the control circuit before the main switch blades break. Switches with built-in electrical interlocks are UL listed. For factory-installed electrical interlocks, add EI (for one contact) or EI2 (for two contacts) to the catalog number. This safety switch electrical interlock kit is for safety switches with a UL certification and an SPDT switch function.