The pack includes the most used sanding grits of 240, 400, 600, 800 on two small blocks
Each block is clearly marked which grit you are using.
The firm sponge makes them comfortable to use and can be easily cut down in width and thickness to alter the flexibility for sanding curves. The thickness of 8mm is designed to give a bit of flexibly to work on curved surfaces.
For stiffer and finer options please refer to the NINESTEPS SANDING BLOCKS FIRM TYPE (NSTL005)