Webb Abrasives CBF Combo Sanding Sponge, 2-5/8-Inch x 3-7/8-Inch x 1-Inch

I was sanding some cabinets and the edges couldn't be sanded using a power sander. This works pretty well to get into the nooks and crannies since it's foam but the drawback is that the sanding surface doesn't last for too long. Alternatively, after the surface is rubbed off, you can cut a piece of sanding paper and wrap it around the foam block - it's not a perfect solution, but works ok.

This one is very fine texture, it doesn't specify on the package but I'll estimate 180 grit. The angled edge is handy for corners.