Designed for precise sanding jobs on small, delicate or hard-to-reach parts at just 4 mm, just a bit over 1/8â wide. We recommend using the coarse grits to gradually eliminate the most prominent defects, while the two finest grits should be used to obtain an extremely fine and smooth finish, leaving the surface ready for painting. Can be used on a full range of materials including resin, metal, wood and, of course plastic. It can be used both dry and moistened with water.