【4Pcs/Pack】SIMAX3D Brushless Axial 4010 Cooling Fan Blower High Speed DC 24V for Ender 3 Series, CR-10 Series, Computer Fan

The description says "Low noise: The voice of these cooling fans are lower than 20 dBA, that will be a lower friction and energy consumption, give you a long life for your Fans using, allow your machine to cool down normally.".I bought these to quiet down a 3d printer, after driver upgrades almost all of the 45dBA while the printer was running was fan noise, so 20dBA would have been a major improvement. Unfortunately, while these do move a LOT of air, they are nowhere near that quiet. After replacing the two "loud" fans on that printer with these "quiet" fans, the noise level went up from 45dBA to nearly 70dBA. I'll be going back to the stock fans and returning these.

Seeking quality true double ball bearing fans, I turned to Amazon thinking the listings should be honest. I waited quite some weeks for these to arrive, yet got totally burned in the end, despite my efforts: These are not ball bearing!!!!!! They have cheap sintered sleeve bearings and should cost a dollar or less a piece. (See photos)I paid a high price to get the quality and peace of mind I wanted, And then paid an even higher price getting subsequently burned. I really wish that AMAZON would do a lot more to prevent these types of experiences, or that there was somewhere else I could conveniently buy things like this and not get burned!

these fans stink. 4 of them burned out in a month

Using them for an open source printer