Package Included: 20PCS Reducing Noise Anti-vibration PC Case Fans Computer Cooling Fan Mount Soft Rubber Screws. Color: black. Material: rubber. Length: 40mm / 1.57". Features: Made of high quality silicone rubber, great flexibility, ultra-soft, aging resistant, and a long service time to use, can be used in high temperature. Function: Replace box fan fixing screw, reduce box resonance caused by fan vibration and anti-noise during PC case fan mounting. Reducing noise of fan and shock absorption between the fan and the PC case, eliminating vibration helps to reduce stress. Application: Universal-Design fits most open cases fan sizes and PC cases. Extremely convenient and quick for mounting and unmounting.