Didn't know HeatBit, but that's in a different price category, similar to FutureBit. Price x 10 is market / 10. What's nice to see is they pop up in wide price and power ranges.
The cool thing about heatbit is they're engineered to work as low-noise heater/air purifier combos, so they're really no expensive than a normal appliance, but give you free sats.
Reading their website, looks like a premium device with a combination of heating and air purification. Watching the teardown now. They also have a good copy-writer, there's some funny stuff on there. 😄 https://m.primal.net/Irpd.png