While these are excellent sanding sponges for freehand use, they also have a grip backing that allows them to be mounted on the hook facing of a 3" × 4" Mirka orbital sander platen or Mirka hand-sanding pad.
Suitable for use on hardwoods and on flat or gently curved surfaces, the sponges have a 5mm thick backing made of high-density polyurethane foam. The pliable, durable foam maintains even contact with the work while cushioning your fingertips so the sponges are comfortable to use for long periods.
They come in nine grits from 36x to 320x. Made in Finland.