I love the these heaters. They have always been reliable, and I like the fact that there's a digital easy to read Guage as well as easy to adjust the temp

UPDATED: After having this replaced and functioning for a week, I feel I can give a fair review now. I raised from 3 to 4 stars. 5 stars if what the setting I leave it own is consistent. In my 8 gallon, I think it's perfect, however to give it a fair assessment, I thought I'd see where it stabilizes and as it's tweaked for the first 48 hours. The temp I want is 80F. After it stabilized at 78F, I gradually raised it. Mind you, the dial is on almost 90F for it to stop there. Then, gradually I raised it and achieved 80F to 80.5F which made me happy for about 3 days.
Without any changes in the whether, nor lights on in my tank, nor change in the temp inside my house (which is set to 75 now in winter) this thing started jumping up the temp. First I saw it go up to 81 from morning to late night on the 6th day (3 days after reaching the constant 80F I wanted.) I though nothing of it. The next morning it was in the low 82s. It got my attention. By night that day I saw it read 83F and I started to panic. There was nothing I changed, and the tank is clean of algae and all. So why the sudden spike? I don't know. Needless to say I was stuck monitoring it all day as I had to again adjust the dial. Bringing it down back to 80F (with having to adjust the dial back down to the 80s, and gradually back up to almost 90.)
It's been 80ish for almost 2 days.
I would just recommend that this be monitored closely the first week. Also, don't trust that whatever temp you set it on will be the temp it will auto stop on. It doesn't seem to know if the temperature it's set to has been achieved. Had I not intervened, my fish would be dead. I'm happy that its keeping the water from spiking to the low 70s for my betta. But I'm bit too thrilled that I still had to out hun through getting to a nice warm temp and normalizing, then getting hotter on it's on, and then having to being the temp of the water back into the 70s to get it back to a constant 80. So far, it's at 80ish. Works, but needs tweaking and monitoring. And atleast the replacement disnt come with a broken bulb like the first one initially did.
That's an honest review.

OP:
I bought this to heat my small tank almost as an emergency. The description is perfect and exactly what I need, however, the glass was broken. Amazon told me this is a 3rd party and they can't expedite it, but they'll replace it since it's under 20 bucks. I'll see if the replacement arrives when and as expected.
BIGGEST Concern: Now, I'm forced to wait another 3 days with my Beta cold, and in order for me to keep him warm I have to have the heater on in my house 24/7 so the temp stays consistent. Needless to say, this makes sleeping at night for us very uncomfortable as we are used to having the AC on at 65, or when its winter like it is now, we just keep the AC off since it gets cold naturally.
It was packaged well from the Seller, as you can see- the glass tube even has a protective foam sleeve over it, and the whole unit is inside a fairly sturdy box- however, the main packaging it arrived in was an envelope instead of an Amazon box. Amazon boxes have 2 extra layers of protection- the cardboard, and the bubble wrap.
I recommend the buyer chip in a little extra, to make sure Amazon packs anything with glass, in a box and not these yellow envelopes.

As for the unit, it's now an electric rod that will electrocute anything since it plugs directly into the 120V outlets. It's going in the trash, and the cheap little thermometer is going to just be an extra one in case the other one breaks- because I'm seeing a lot of reviews of it being the main thing that breaks or malfunctions quickly.

* I will change my review and update upon delivery if it arrives as was told to me, and after I've used it a while.
REVIEWS here are based on the immediate results seen after people use it, but only in the first 24 to 48 hours, usually. I don't think that's a fair assessment of ANY product. Reviews like, "Plugged it in and works!" or "Put it in my tank and it heated up to the temp I programmed it for," don't really say if it works correctly- and most importantly if it lasts a decent amount of time.
I'll update mine after having it a couple of weeks, because that's what we REALLY want to know- not that it works out of the box, but that it does what it says once in use for a while.

Although there are slightly cheaper heaters for sale, these ones adjust to the temperature you want and automatically turn off to prevent overheating unlike cheaper heaters. Both came with high-quality digital thermometers which was a wonderful bonus. They read within 0.5°F of each other when placed in the same tank, and having two was nice for acclimating fish to the heated tank so I could be sure that both water temperatures were the same. I ran the first one I set up for 24 hours with no fish to test the temperature (and used a thermometer not included to compare) and the water temperature stayed at or slightly below the temperature I set. If you are deciding between two temperature settings (they're in increments of 3°F I think) I would recommend the higher one because the thermometer will turn off when the set temperature is reached, and the tank will cool a few degrees before it turns back on. I'm very impressed with this heater and am glad I bought two. The digital thermometers are a lot more accessible than the ones I had because you can check the temperature with a glance from the other side of the room instead of having to get close to the tank at the right angle and squint to see the mercury inside the other one, and you can move them without getting your hand or whole arm wet. I'll keep them off except to check the temp after a week or so of good use so the battery doesn't run out. It takes a couple hours for them to heat room temperature water to the warmth I wanted so I would recommend starting with warmer water if you don't want to wait.

Update: 48 hours later, after putting the second one in my 3 gallon tank, the temp was up at 88°F despite being set on 81. Not super concerning, and likely just because this tank is smaller than the other and is near another source of heat (hydroponics heater). I turned the setting down to 77 and added a few ice cubes to speed things up and will update if the temperature stabilizes at the desired temperature (80-84°). I have no fish in the tank as I typically don't with new tank devices for 24 hrs. This is partially my fault for keeping such a small tank in an area where the temp fluctuates a bit, but I expected the heater to turn off as a result of the added heat. The temp outside the tank is 76°.

Update to the update: the temp fluctuation was most likely a result of a semi-rapid increase in room temperature. We usually keep the house at around 68° but when the sun comes in the big SW windows in that room and the door stays shut, the room rises about 10° over a few hours, which must have been enough to raise the tank temps for a bit, especially if the heater had just shut off. I kept the setting lowered on the one heater and have been monitoring the temps and they are clocking in (or thermometering in, if you will) within the desired temperature range.

These reviews had me scared my fish was going to fry while I was at work. When I got home he was completely fine. The reviews said it is about 3 degrees off. So if you set it at 77 then it is around 80. For me this hasn't been the case. It has been very accurate. I am not sure what everyone's tank size and what watt power they're buying for this heater. I have a controller that I plugged my heater into. So it detects if it gets too high or too low. This is just extra precaution because heaters no matter cheap or expensive can give out and the thermostat inside can break. I would recommend investing in one of these. It can be confusing setting it all up. The one thing I didn't know is to calibrate it. This allows you to set the accurate temperature. So if it is off by a few degrees you can adjust it to be correct. This will help with the heater and all that fun stuff. I've had this set up for a week now. So far everything is working as it should. The heater is accurate for me. I would recommend buying a reliable thermometer and not one that is cheap from the pet store. Mine worked for about a day and it's now been stuck between 70-72 degrees even though my tank is 77 currently. Trying to save all of you stress because you see that it reads 70 which in my case would be below the minimum I should have for my Betta. And then you crank up the heat and end up frying your cute guppy because you thought it was too low. Definitely look into extra precautions like the heater remote. This will save you so much anxiety and stress knowing that if the heater malfunctions and continues heating past said temperature"¦it will shut off depending what temp you have set as your desired temperature on the remote. I'll update if anything changes! So far only positive.

The item does what it should. It was a very easy set up. Extremely affordable. Was actually highly recommended by an expert in setting up/maintaining tanks. I'm glad I took his advice and made the purchase. So far so good. Certainly cheaper and better quality than anything we could have gotten from our local pet stores.