4 channel extension module for time switches TR 641 top2 RC, TR 642 top2 RC and TR 644 top2 RC, DIN rail housing, width 4 HP, 4 external button/switch inputs (one input for each channel), switching preselection, permanent ON/OFF switching, 4 LEDs to display the switching status, zero-crossing switching, DuoFix spring terminals for 2 conductors each, 2 changeover contacts 16A/250V and 2 changeover contacts 10A/250V