SIA Abrasives foam is long lasting, giving you multiple uses. sia Abrasives has developed a colour coding system that is easy to understand and allows you to never mix up your sanding grits again. Each colour represents a grit range/grade, this block is yellow, indicating a fine grade. This block is 4-sided and features an angled side to ensure easier use and to sand round profiles. The siasponge is easy to clean and also offers low clogging from sanding dust because of it's more flexible binder and soft carrier material, which removes sanding dust continuously, resulting in a longer life.