Time Clock Internal, Reliance, 24HR, 230V, DPST w/ On/Off Tabs : M521-3-240

Mechanical time clock with a battery back up, the M series are the clocks for you. 40 Amp DPST time clock with 120 hours battery back. Add a relay for your photocell and it becomes the M221AP. Found on old Len Gordon controls and modern Diehl Controls.