This pack contains the common screw inside the computer, they are suitable for PC case, power supply, motherboard, hard drives, fan and floppy/CD-ROM/DVD-ROM drives fixed installation, they are placed in a box, easy to find and use! 【set screw assortment set Material】： All computer screws are made of high quality brass, steel and fiber paper, steel with nickel and black zinc plated which have superior rust resistance and excellent oxidation resistance. Warning: small parts, keep away from children under 5 years. 【 After sales Service 】: If there are any problems with our set screw assortment set ,please contact us and we would be very happy to solve your problems..