Dimension of outer the frame is 80mm(L) x 80mm(W) x 25mm(H) / The size of fan in inch is 3.15in(L) x 3.15in(W) x 1in(H); The center to center distance beween the mountiong holes is 71.5mm/2.81in. Operating Voltage Range4.5V to 5.5V. (overtake to 5.5V, it can also work. but not safe, and seriously affects lifespan of fan.) Rated Voltage: DC 5V; Rated Current: 0.25 Amp; Rated Speed: 2500 RPM; Air flow: 39.7CFM; Noise:26.8dBA Connector: USB Plug; Bearing Type: Sleeve Bearing ; Life: working up to 35000h at 25 degrees. Package include: 1 x 80mm cooling fan; 1x 80mm metal grill; 4*M4x35mm screws & nuts( The metal grill is separate with fan and it is mounted by screws.)