These are, as far as I know, the only timers that have designated "on" trippers and designated "off" trippers. I plug my crock pot or other device into this when I want it to turn itself off if I forget to do so. So, I just install only one of the "off" trippers. I place no other tripper on the wheel. I use the manual switch on the timer to power up the crock pot and set the "off" tripper at some time when I want it to turn off. Then, if I am going to be really late coming home, I know it will shut off before a dry crock pot starts blazing. And, because I only installed an "off" tripper, it will never start up the crock pot again on its own.Other timers that have trippers have trippers that are all the same. If I used one of those, then the timer would turn off but it would also start up the crock pot the next day when that tripper was encountered in the next 24 hour cycle.I like to slow cook meats over 12 or more hours and I put it out in the garage so it doesn't stink up the house. (Lots of spices, chilis, and onions slow cooking over many hours can impregnate your drapes, carpets, and woodwork with aromas that won't go away for days and days...so I put it in the garage.)I could certainly envision a day when I set the food to cook, but I would get called away on a late night job, It would be just like me to come home tired, go to bed, and forget entirely about the food cooking in the garage. In good weather, I'll park my car outside. It could be days and days before I remember the food in the crock pot out in the garage.With this Intermatic timer, no problem. Fire department didn't have to come. It shut off the crock pot and won't start it up again, and again, and again like other timers would do.These timers will work with inductive, resistive, magnetic fluorescent, and electronic fluorescent, including twistie bulbs. It's got a 15 amp 3 prong outlet. Motor turns the wheel. Simple. Reliable. I like it. The operative logic of such a simple device is bullet proof.What if the power goes out? It starts up again when power is restored. But, oh, you say, your food will be rotten if it's off more than a half hour? No problem, Just look at the wheel when you retrieve your food. You set the wheel for the correct time when you started cooking. If the time is off more than whatever period you think is unsafe to eat? You will know.