This was the last in the line of large single station recorders in wooden cases that started with A. A. Newman's clock patented in 1880 (I.D. 712).  With this model, the face and hands were given up, but the seven-day dial which first came into use with the earlier Regulator No. 2 was continued.  Seven-day coverage had such general utility value that it became the standard in all subsequent Newman and Detex single-station clocks, the "Sentinel," "Safe-T-Chek," and "STC-7000," but in all models subsequent to the Guardian the size of the recording dial was greatly reduced.