Birkenstock Birko-cell Foam Spacer Various colors Birko-cell Foam
If you have shoes that are too loose, this is the perfect solution. Place this spacer underneath any removable footbed and make a loose shoe or clog fit just right. 3 mm thick Birko-cell is a washable and durable non-absorbent foam you can cut-to-size.
Sold in wide widths, but you may trim with scissors to fit your particular shoe style.