Flexible Fine/Medium Sanding Sponge @ The Painted Heirloom
3M SandBlaster Pro 220-Grit Sanding Sponge 2.5-in x 4.5-in (2-Pack) in the Sanding Sponges department at Lowes.com
10 Pcs Fine Sanding Sponge Sheet Block Pad For Metal Plastic Wood 240-320 & 400-600 Grit - Reusable - Tool Parts - AliExpress
Amazon.com: ADVcer 500-2000 Grit Sanding Sponge 8 Pads, 4.5" x 5.5" x 0.2" Assorted Wet or Dry Ultra Fine Hand Sanding Sponges, Flexible Soft Foam Sand Block for Drywall, Corner Contour, Metal