for Reference only:

• DC Fans usually come in 5V, 12V, 24V or 48V. Computer fans, PC systems fans, CPU cooling fans, Chipset fans, hard drive coolers usually use 12V DC fans or 5V DC fans.
• Ball Bearings & Sleeve Bearings:  Ball Bearings are better quality bearing option for fans. Ball Bearing Fans last longer but have higher temperature ratings and it is noisier. Manufacturers also make Double Ball Bearing Fans to extend their life circle or Single Ball Bearing Fans to cut the costs. Sleeve Bearing fans are a less expensive and less robust alternative to Ball Bearing fans.
• Ceramic Bearing: Ceramic bearings are rotary bearings constructed of ceramic. Ceramic hybrid bearings, the most common type of ceramic bearing, are constructed of steel inner and outer rings with ceramic balls in place of steel. These bearings have several advantages over all steel bearings, such as higher speed and acceleration capability, increased stiffness, higher accuracy, lower friction and heat generation, reduced lubrication requirements, low thermal expansion, and extended operation life. Bearings containing all ceramic balls are also nonconductive and are commonly used in electric motor applications.  Nanometer Ceramic Bearing ( So called Ceramic Bearing, NC Bearing, NCBearing, or NCB ) has longer Life Span ( Double Hours of Sleeve and Ball Bearing ), lower noise, better Durability, Anti-Shock/ Anti-Vibration, Water Proof, Resistant to Oxidation and Chemicals.
  Compare NCB to Steel and Copper on Hardness (HV) and Extension Coefficient (ETC 10^-6/˚C):
  NCB - 1340 (HV), 3.0~8.3 (ETC 10^-6/˚C),
  Steel - 560 (HV), 11.2~14.3 (ETC 10^-6/˚C),
  Copper - 240 (HV), 20 (ETC 10^-6/˚C).
  Info Source: Global Win Technology Co., Ltd.
• Heat Pipe: A heat pipe is a simple device that can quickly transfer heat from one point to another, which is usually used for cooling an electronic component in air-conditioners, refrigerators, heat exchangers, transistors, capacitors, etc. Heat pipes are also used in laptops to reduce the working temperature for better efficiency.
• Hydrodynamic Bearing ( HDX Hydro Dynamic Technology ): hydrodynamic bearings are fluid film bearings that rely on a film of oil or air to create a clearance between the moving and stationary elements.
• VAPO Bearing & MagLev Design: Vapo bearings are made of a material specially treated for wear-resistance and impact-resistance. When used in conjunction with the MagLev, it creates a spring function, which helps the fan motor to bear impact. MagLev design helps the rotor to rotate evenly in a fixed orbit within the orbit center without any friction with the bearing bore. No vibration occurred. This new system eliminates the use of oil rings and washers, thus leaving space for the release of gas occurring during normal operation. No more clogging problems. Vapo bearing is named after this character.

• CFM: Cubic Feet per Minute (airflow).

• DC Fan Power Connector: Computer fans usually get its power from switching power supply with Molex 4-pin power connector or with 3-pin PC Mother Board connector to be connected to the system's main board. Sometimes the DC Fans also come with different types of 3-pin, 2-pin connectors or just with bare wires.
• Brushless DC fans: Most computers use brushless DC motors since they are clean (no brushes to create carbon dust or to wear out) and are now smaller and less expensive.