 The hotter and colder temperatures are usually established simply by sliding two levers along an analogue temperature scale, much the same as in a conventional (non-clock) thermostat.This design, while simple to manufacture and relatively easy to program, sacrifices comfort on weekends since the program is repeated each of the seven days of the week with no variation.To overcome this deficit, a push-button is sometimes provided to allow the user to explicitly switch (once) the current period from hot period to a cold period or vice versa; the usual use of this button is to over-ride a "set back" that takes place during the workday when the home is normally unoccupied.