For many industrial applications, Square D is a top manufacturer of safety switches. Square D safety switches meet the highest standards of mechanical endurance and reliability, providing significantly higher levels of performance than NEMA KS-1 requires. The F-Series safety switches, in particular, are built to last, with a minimum design life of three times the NEMA requirement. ... https://www.partshnc.com/m/schneider-electric-square-d/square-d-safety-switches