Review on WINSINN 40mm Fan 24V Dual Ball Bearing Brushless 4010 40x10mm 🌀 - High Speed (Pack of 5) - Enhanced Airflow Cooling Solution for Electronics by Aquarium Lanter

One of my fans was missing a blade that was not in the box. The box has also been sealed with a sticker, meaning whoever packs it at the factory doesn't test it. Of the remaining 4 fans that all had blades, one of them has a pretty bad fan whistle. It didn't look defective (at least from the outside as far as I could tell) but it didn't sound like the other 3. Airflow wise they're pretty good. Much better than the stock fans that came with my Ender 3. In terms of sound (3 fans work normally) they are about as loud as standard fans. A few notes: they are actually ball bearings. Unlike some fans that claim to be ball bearing but are double ball bearing as described. That means they should last a relatively long time (I'm sending mine back, so I'll never know for sure). These are also 7-blade fans for anyone interested as Winsinn shows both 7-blade and 9-blade fans in their photos.