Noiseblocker NB-BlackSilent Fan PM-2 40mm x 20mm Ultra Silent Fan, 3800rpm, 3 pin, 17.7 dBA, 5.41 CFM Noiseblocker NB-BlackSilentPro PM-2 3800rpm Fan speed 17.7 dBA Noise level 5.41 CFM 40mm x 40mm x 20mm