SurfPrep uses 2 different densities for our foam abrasives. The 5mm and 10mm foam abrasives are a gray closed-cell foam with a firm density. 5mm pads are great for flat surface sanding. 10mm pads are great for flat surface sanding, dropping into cabinet faces, and working on soft profiles.
The ½” foam abrasives are a light faint white colored open-cell foam and are “squishier” to conform to complex details, moldings and profiles.