This Indoor Electronic Programmable Plug-In Timer with Top LCD is an excellent choice for regulating your interior lights and other electronics into an automated on/off cycle by setting up to 20 programs from one to seven days a week. Programs can be set as an on/off timed function, countdown function and three modes of random functions. It also functions as a clock with an optional daylight savings feature. With batteries installed, you can move the timer from place to place without losing the programming memory. Use it for a few indoor lights to keep you from coming home to a dark house or to give your home that lived in appearance by using the random function to help deter criminals while you are away. A manual on/off button is a convenient option if you wish to override your current timer status. By limiting the amount of time your lights are on you can significantly reduce the amount of energy being used and eliminate the cost for that energy. It is a great low cost way to automate your lighting up to 1800W (or 15A) and control the amount of power they are using. # Heavy Duty Indoor Electronic Programmable Plug-In Timer with Top LCD # Owner's manual # Two button cell batteries .Sometimes trying to program electronic devices is difficult and counterintuitive but you will have this indoor timer programmed in no time. The included instructions lead you through the initial programming in an easy to follow, step-by-step process. With this timer you can program your lights on a 7-day cycle, which gives the illusion you're home when you're on vacation. Give yourself added safety and security knowing that your home will have that lived in appearance while you are gone. With the random function on "short" your lights will turn on and off between one to two hours, on "long" for two to four hours, or you can program your own random times in a specific one to two hour range. Battery Backup The batteries serve to back up the clock and programs while it is unplugged. The battery life is around 1 year when the Timer is not connected to the power outlet. If you plan to leave the Timer unplugged for a long period of time, you may want to remove the batteries from the Timer.