Brushless DC System Fan 1.frame size(mm):254X254X89 2.bearing type:ball bearing 3.max air flow:688CFM 4 ... .max noise:66dBA ADDA AK258 Brushless DC System Fan ... detailed specification:1. frame size(mm): 254X254X892. bearing system type: ball bearing,3. rated voltage:115V/50,60HZ, ... . safety approvals: CE,TUV, UL,cUL Brushless DC System Fan 254X254X89mm