What is Reddit's opinion of BULLETSHAKER Camping Mini Heater Warming Stove Cover Tent Heating Cover?

From 3.5 billion Reddit comments

If you have a butane camp stove for cooking, the heater sits on top and creates quite a bit of heat. I use it when the interior gets cold to keep it comfortable. I don’t want to be in a sleeping bag or with multiple layers when I’m inside and it’s cold outside.

The only insulation I used is a closed cell foam with adhesive butyl backing on one side and Reflectix on the other. It comes on a roll and you cut it to fit inside the interior panels, headliner, tailgate, etc. All other odd and small spaces are filled with a loose, mold resistant insulation. The difference is pretty big temperature-wise. The interior stays warmer/cooler longer and the sound deadening is amazing. Between the insulated window covers I made for all the windows, including the windshield and back glass, the insulation, and heating/cooling solutions I’ve cobbled together, the water side of my mid size SUV is comfortable no matter the weather.

Got a stove? Try a stove top radiator. You'll still have to ventilate out the CO and moisture, but it'll consume less fuel if you like, is more adjustable, more packable and works with any fuel source. Oh, and you can make coffee on it while it runs. Here's something similar to what I use:

https://www.amazon.com/Camping-Heater-Warming-Heating-AdvancedShop/dp/B0768H9BJQ/

I've no insulation in my Astro. I use a stove-top radiator like this, and it's just enough:

https://www.amazon.com/Camping-Heater-Warming-Heating-AdvancedShop/dp/B0768H9BJQ

There's caveats. First, I don't choose cold climates, I only go to sub-40° F climates when I have to for work or booger up and climb too high up a mountain or something. I don't have a CO detector, but I smoke cigarettes like a chimney, and as such maintain good ventilation and check up on it every hour. I don't run the stove while asleep, at all; I'll kick it on for an hour or two after climbing in at night, then kill it and go into burrito mode at first yawn, then maybe run it for 30 mins or so after getting up and out to pee at night or whatever. I find I can stretch a $10 tank of isobutane to ten hours' usage on just the heater, though, and while mine isn't the exact one I linked, most of them can cook at the same time; good dual purposing for tiny interiors and makes for a cozier coffee time in the morning. It's made 19° F nights better than bearable for me.

But I'll stress it again... Do not run these while asleep, and make sure you are ventilating very well, or this option will KILL. YOU.

To exchange heat between the stove burner flame and the surrounding atmosphere you need nothing. 100% of the heat generated by the flame will be in the air above it. A small fan might circulate the hot air horizontally so the ceiling doesn't get all the heat. I sometimes use a 1.5 inch 12 volt square fan mounted to one side blowing across the flame 12 inches above.

According to the Amazon ad https://www.amazon.com/Camping-Heater-Warming-Heating-AdvancedShop/dp/B0768H9BJQ/ the inner can gets heated by the flame and radiates the heat by infrared. The Mr Heater uses a hot ceramic to radiate the heat mostly in one direction. The round can radiating in a 360 degree pattern doesn't seem like much of a focusing.

The high efficiency claim is absurd. Unless it leaks some heat outside it is 100% efficient.

A furnace that dumps combustion waste (CO2, water) outside will have a heat exchanger with flame on one side (outside) and indoor air on the other. The heat gets exchanged from one side to the other while keeping the two masses of gas separated. This can with holes doesn't exchange heat from the exhaust gas to the indoor gas. It allows the two to mix. Since there is no chimney there is no loss of heat up the chimney.