Noctua (NF-A14 ULN - 140x140x25mm Square Frame Fan, 3-pin, 800/650rpm SSO2 Bearing - 2pk Square Frame: 140mm mounting holes (124.5mm spacing) makes it a premium grade replacementand perfect for use on 140mm water cooling radiators. Ensures full coverage and best pressure performance. AAO Frame: Integrated anti-vibration pads, Stepped Inlet Design, Inner Surface Microstructures. All further refine the fan's performance/noise efficiency. Flow Acceleration Channels: Leads to better efficiency and lower vortex noise. SSO2 Bearing: Provides even better stabilisation, precision and durability Metal bearing shell: a CNC milled bearing shell made entirely from brass provides the highest possible degree of manufacturing precision, minimum tolerance and excellent long-term stability