Does anybdy know what it is? The keybed is a matsushita sk-949, thanks.
Never had one myself, but when there isn’t an already identified replacement felt for sale here or elsewhere I just open it, and measure a non compressed region, and buy a small quantity from McMaster Carr or even Amazon. The Sigma I did recently needed 3 different thicknesses. BTW, if you haven’t replaced the smd caps in that bird, you’ll need to soon. It got a bunch of the poor quality ones that have been failing like crazy for 5-8 years.
Felts are generally unobtanium and refurbishers have to find bulk fabric replacements and cut them to size.
Have a look on amazon for keyboard felt, or piano felt. Another option is your local musical instrument repair shop may be able to source something similar.
Once you find something that’s suitable, replace all the felt to keep the keyboard pressure uniform.