Siemens 3SU1050-5BN21-0AA0 Actuators and indicators, 22 mm, metal, shiny. Siemens 3SU1050-5BN21-0AA0 is the exact printed commercial reference for a pilot and control device in the SIRIUS ACT 3SU range. Siemens' official product description is: Siemens keyswitch, C, 22 mm, round, metal, shiny, lock number S-10-CG, with 2 keys, 3 switch positions I-O<II, latching on the left, momentary contact type on the right, actuating angle 2x45°, 10:30h/12h/13:30h, key removal I.