[Case Fan] The company making these fans is aptly named. These fans are dead quiet. I changed these fans out on my son's computer and started the machine up. At first, I thought I did something wrong because I couldn't hear the fans, but the computer was on! The fans are a must if you don't want the constant droning of those older and louder fans. Highly recommend these!

[29.3 dBA] Great fans.

Have to look into the case to see that their working.

[78.4 CFM] As usual, the be quiets packaging of this PC cooling fan truly compliments its high-end design features and manufacturing quality control standards. Note however, that once the taped seals of the cover's front panels were cut on both pairs of fans I had just purchased, my careful attempts to pull out the inserted locking tabs of their front panels to be very frustrating.
And all of this care spent to keep their cartons intact, should I decide to re-sell these fans. And it's my guess that all my frustrations were due to the thick, high pound test construct of the carton's material, plus the bit oversized latching ears provided along the sides of these locking tabs.
And as for noise levels, with 60 dBA being that for a nearby, average-sized, refrigerator, plus 30 dBA being that of a nearby whisperer, and once the noisier, fast run-ups are achieved, the subsequent steady state noise is definitely less than top-speed rated 31.2 dBA.
And take note, have my fan pair installed as optional CPU Fan #2's in my second budget build gamer, featuring Fractal's Focus G mini-tower, with an AMD Ryzen 7 over-heating prone 5800-X CPU, being cooled by it-s installed be quiet Dark Rock Slim cooler, and driving an AMD Radeon RX6600 GPU, with a be quiet's Dark Power Pro 750 Watt for power. All installed on a ASUS TUF Gaming B550M-Plus WIFI II motherboard. Plus, a must replacement of the Focus G's front fans with Fractal's GP-12 PWM fans.
And this combo keeps the at above idle CPU temps at 47-50 degrees C, even with BIOS DPM activated, and its ASUS optimized settings red-icon activated. And these be quiet CPU Fan #2's are running at constant 1700-1800 rpm. And all total, maintaining my peace of mind for the extra costs of these PWM fans chosen to install. And have yet to do several runs of the on-line gaming performance evaluators.

[78.4 CFM] The quietest fans I've ever used, keeps case cool. Well worth the money.

[4-Pin] Very high quality, quiet and efficient fan.

[140 mm] Already had a bequiet fan and I wanted to stay all in the family with the rest of my fans in case they produce different tones when spooling up. The unique looking fins and fan shape brought me to this brand. Works fine, moves some air, keeps things cool, and stays quiet.Recommended.

[1900 rpm] easy install, near-silent operation. you can't get much better than Noctua when you take into account performance and warranty. these fans are worth every penny

[29.3 dBA] Quiet and easy to install

[0.865 lb] I decided to replace the brown Noctua fans that were visible through my case window with black fans. I'd read good things about BeQuiet and decided to try two of its fans. First impression was the weight of the box. The fan itself was noticeably heavier than the fan it was replacing. Installed it as the rear case fan and booted up the system. It almost feels like a wind fan blowing behind the case. The fan itself is very attractive and really improves the look of the case. I swore I'd never use anything but Noctua fans. But after trying BeQuiet, I'll definitely consider them in the future.

[78.4 CFM] I am not using these fans for cooling my computer, but for moving warm air around my camper. They are quiet and able to move warm air from the main section of my camper to the bedroom. They also draw only an amp or so and thus preserve the battery. 6 year warranty and well made.

Highly recommended.