You have to be very careful when selecting cloth for Penta frets as the original stuff is very lightweight. Anything of a heavier knit than the original fabric and your frets will not clip back on absolutely correctly and shake themselves off over a period of time due to the extremely tight tolerances of the clip positions.
I know this from experience😂 Mine are now blue (thanks to member Kevin) after reclothing in the black stuff from Maplins which did what I have described above. Also not a job for the feint hearted as the corners on the top frets are a complete and utter pain in the derrier to get right. I'm happy to do the work for you or offer assistance if you can source some reasonable material though.
Chris.