Thanks for the info. MDF - medium density fiberboard.
Replacement Speaker Grilles
This isn't a question, just a heads up for those looking to replace their speaker grilles.
I love my vintage JBL loudspeakers. I have a pair of L100T's and a pair of L100T3's. The plastic grilles on them are vulnerable however. The grille pins that slide into the rubber retainers are prone to snap off. Replacement factory grilles have proved to be impossible for me to find.
I did find someone on EBay that sells them that he makes himself. These are GREAT to say the least! They are a precise fit and look like the originals. The fabric covering is available in 14 colors. They make grilles and such for other brands of speakers also.
The best part? The pins that slide into the retainers on the cabinet. They're metal. These are very sturdy and will not break off like the original plastic pins. The grilles themselves aren't plastic either. Mine are made of Multi Density Fiber (MDF), but the material varies depending on the brand/type of speaker grille.
If it's okay to share the seller's link here on Audiogon, it's: