Color:2pack Green Innovative Anti-vibration Mounting System:In all four corners of the rubber pad containing the anti vibration can provide a safe protection, and help to reduce the vibration between the fan and the box to reduce noise Specifications: 120mm fan size : 120 x 120 x 25(mm)/ 4.7' x 4.7' x 1' computer case Speed : 1200RPM+/-10% cooling fan Rated Voltage : DC 12 Volt computer case Bearing Type : Hydraulic Bearing computer fan Noise : 20dB+/-10% quiet for cooling 120mm case fan Max Air Flow : 21.71CFM 120mm fan Connector : big 4 Pin & 3 Pin LED fan Life : 30,000 long life hours LED fan External Material : Plastic LED fan Color : Red , Green , Blue , While LED Number : 15 piece Package include: 2 x Case Fan 16 x Rubber Pads 8 x Mounting Screw Attention: cooling fan has both 3pin and 4pin Connector, please DO NOT connect both interfaces avoid the occurrence of short circuit Q1: why is there no screw thread on the screw hole? Answer: Our fans are made of plastic material, if there is screw thread, it would be easy to slip off. This would result in the whole fan not being able to be fixed or be used. Q2: why is it so hard to screw in with a screwdriver? Answer: Because there are not threaded screw holes, screw need to be pushed hard, so we have a large screw head design. Although the 'small screwdriver' can be barely screwed, but have to spend a lot of effort to do so, and it is easy to make the screw slip out! Therefore, we highly recommend using large screwdriver for an easier and faster installation.