The LA9LC393 is a lockable knob kit from Schneider Electric's Integral 32 range, designed for the LD1 disconnect switch. It allows the operator to padlock the rotary knob in the OFF position, meeting lockout/tagout (LOTO) requirements on the line side of the starter.
This part is officially obsolete per the manufacturer. No direct successor order code is listed. Verify the knob profile matches your existing LD1 operator before committing the line.