Noiseblocker BlackSilentFan XS-2 developed in Germany; silent NB-NanoSLI bearing NEW!; silent NB-EKA P2 Drive NEW! Bayer Makrolon rotor with anti-dust technology; reinforced fibreglass PBT-frame NB-slics for vibration-free assembly 4000rpm Fan speed; 21 dBA Noise level; 8.89 CFM; 50mm x 50mm x 10mm