I purchased this to control lights on my front porch. Programming is fairly simple if you read the directions first. Programing the switch before installation is easier. This switch is for houses where there is no common wire. There are 4 wires on the switch. A line (hot), load (line to the lights) a ground, and a wire for a three-way switch. My house was built in 1982 so there is no ground and since these lights are controlled by a single switch, I only used the first two wires.The battery door opens by prying it open with a small screwdriver. Not sure why they refer you to a YouTube video. The battery door on my switch was hard to open. I needed a screwdriver on each side and it was still difficult to open. After the initial opening, the door worked fine.For the timer to work properly, it needs to be set to your long/lat. The directions refer you to a QR code for this info. I tried this and it took me to a site and requested me to set up an account. Instead, I used an app on my phone. You need the long/lat in decimal degrees and you need it to a tenth of a degree. When I did this, the sun rise and sun set times matched perfectly to another phone app I use. If you use this setting, the light turn on about 20 minutes before dusk and 20 minutes after dawn. You can adjust this as well if desired.The battery is supposed to last a year or so. The directions state the power (circuit breaker) must be turned off to replace the battery. Since I doubt I will remember this, I wrote “ turn power off before replacing battery” on the inside of the battery cover in permanent marker. Yeah, I write small. I also wrote the circuit breaker number. If the power must be off as a safety requirement, I’m surprised there isn’t a label provided by the manufacturer.The switch has been in use for an almost a year now and the battery is still working fine.

Easy to install and works well!

All I wanted was a programmable light switch. I was tired of manually setting the on/off timer every few weeks using the 1960’s Intermatic clock (see the photo - amazing that it still works). But what I got in this product is a full-on astronomical computer with a very thoughtful set of options, way more options than I need. First, the astronomical computer. The software in this device accurately calculates sunset and sunrise, year ‘round, for several latitudes in North America. (Which reminds me: Flat-Earthers need not buy this product.) There are books written on how to calculate rising and setting times using software. This product implements those algorithms. But wait, there’s more: the device automatically sets the day of the week and daylight savings, so that you don’t have to. Impressive.Downside: the initial setup is comically easy, but entirely unintuitive. Other reviewers have complained. I say: appreciate the ingenuity. All this space-age technology, setup with just 4 multi-purpose buttons and a tiny LCD screen. As others have recommended, sit at a table with the instructions for the initial setup, or just a dress rehearsal. You’ll learn it after just one or two times through. But you’ll quickly forget the steps because you won’t need to touch the device for a year or two when the internal battery needs changing. Anyhow, it all takes maybe 5 or ten minutes. I guess one way to have improved it would be to add a smart phone app that does the setting over Bluetooth, but then you’d have a different set of problems. I haven’t reviewed all the other options, such as the random on/off to fool your neighbors; the different settings for days of the week; etc. but they are all there. This is obviously a well engineered product that has evolved to a high level of sophistication over time, sold at a consumer-level price. I’m so impressed.PS: there’s something deeply satisfying about upgrading the post-war mechanical Intermatic device, 50 years later, with a high tech Intermatic device. America! Heck yeah.

Instructions were difficult to follow for setting schedule. Unlike its predecessor, turn off time is on a different setting from turn on, (eg it is now “schedule 1 -turn on, schedule 2 -turn off). It used to be schedule 1 on and off all one setting. I called the hot line and a very knowledgeable lady talked me through it in 5 minutes. They need to be more explicit in the last part of the instruction sheet. The unit itself is excellent. I appreciate it being able to turn on at sunset and off at 11PM saving electricity with the varying day length. PFS

+ El envio - come siempre - sin ningun problema.+ El producto como esta en la descripcion, facil de instalar y viene con guia de instalacion y manual para configurar.+ buena calidad, solido y muy funcional+ muy buen precio para lo que recibi- las zonas Norte, Medio y Sur son para los Estados unidos, para el sur de Mexico hay que usar sur y aparte ajustar el horario de prender/apagar para que se adapta bien a los cambios cuando obscurese. No gran problema, pero no ideal.- el producto no incluye la tapa, hay que pedirlo aparte.Resumen: muy funcional, ayuda mucho para automatizar y olvidarse de prender/apagar luz y sigue conservando horario y configuracion gracias a la bateria incluida.

El producto es muy simple de conectar y una vez que entiendes y programas su uso trabaja bastante bien. Gracias.

The product seems to work well. I had been searching for an in-wall timer that 1) worked, 2) didn't fail after a few weeks or months, and 3) could self-adjust with the seasons. The ST01 seemed to fill the bill, and others' generally favorable reviews convinced me to buy two of them, one each for the front porch and back porch lights. My lights are CFLB's, and the timer handles them just fine (note: not all timers will work with fluorescent lighting).It was easy to wire them in (I was replacing simple single-pole switches), so installation was no problem. However, if you're not electrically savvy, you would be well-advised to enlist the services of a qualified electrician, so that it gets done "right".The device is battery powered (it's NOT powered by the 110V supply into which you're wiring it). Being battery-powered makes it convenient to set up and program PRIOR to installation, as suggested in the instructions. The battery is in a little drawer that slides out from the front of the unit, so it's easy to replace. However, it's an unusual battery, so be forewarned; it's not your typical AA or AAA cell.The written instructions are "OK", but there's a LOT of "fine print", and it can be difficult to follow all of the steps required to set up and program the device. A much BETTER alternative is to watch and follow the online video (available on Intermatic's website and on YouTube). The video takes your through the setup and programming procedure, and makes it much easier to complete the sequence of "steps" required.A couple of caveats: First, in one setup step, you select the "zone". I erroneously assumed that "zone" referred to "time zone". Not. They divide the US into "zones" by lattiitude: North, Center, and South. There's a little map included in the printed instructions that illustrate these zones, and you simply select the one for the area in which you live. I live in Texas, which is in the South zone.Second (I overlooked this both in the instructions and the video), if you're going to use the astral capability of the timer, you need to specify YOUR times for DAWN and DUSK. The assumed times (based solely on zone selection) are probably not correct for where you live. You can get the actual times for sunrise and sunset in your locale from a number of sources, including online, a TV weather report, or an app on your phone. Once you know the actual times of sunrise (DAWN) and sunset (DUSK) you enter these as part of the timer's programming sequence.Once you've gone through it a couple of times, you get the hang of the programming sequence, and it's really not that difficult. So once you've installed it and have it working, you can make adjustments to tweak it to your liking. I did this and the timers now turn the lights on at dusk and off at dawn. Presumably, as the seasons change (e.g., the days get longer), the on/off times of the lights will change accordingly.Note: This timer has other features not covered here, such as automatic switchover to DST, multiple on/off times, random on/off times, etc. It seems to be a pretty robust device, feature-wise. Chances are, it will handle whatever application you have in mind.All in all, I'm quite happy. I'm writing this review only two weeks after having installed my timers, so time will tell. ;-)