From the 1980's upto the late 1990's the majority of the popular home computers used floppy disks as one of their main sources of data storage and in the case of the Commodore Amiga and Atari ST, it was their main source of data storage.
This means that the disks for the retro computers are now 30 to 40 years old and unless they have been stored in ideal conditions it will mean that a lot of them have become dirty or have surface mould on them which results in read errors, stopping your favourite games and utilities from loading.
This is where the Floppy Disk Cleaning Kit can help. The kit gives you the tools required to easily clean your disks and hopefully bring them back to life. There are three kits available depending on the size of disks you need to clean.

3" - These disks were popular on systems such as the ZX Spectrum and Amtrad CPC. They were also used in other products such as keyboards and sewing machines.

3.5" - Probably the most popular size used by the Commodore Amiga, Atari ST, PC and Apple computers. Again, they were also used in other products.

5.25" - Used in home computers such as the BBC and also earlier in the life of the PC, but also in some other products as well.