This programmable timer (110v) is variable in 30 minute increments. Can go off and on every 30 min. or on at 9:00 p.m, off at 11:00 p.m etc. To use, set the dial to your specs, plug into wall outlet, then plug your diffuser into it. Includes on/off switch that allows you to turn off without losing programmed settings. (Also works for lamps and small appliances - has 2 outlets.) Features: * Easy to Set * Repeats Every 24 Hours * Non-Removable Pins * Polarized Plug for Extra Protection * Convenient Override Switch