F-15 (minimum 55% wool) and F-55 (minimum 80% wool) black are the two industrial felts recommended for use as acoustic panels.

Olympia Typewriter, Replaced Felt On Inside of Top Lid Cover, Repair Detail<br /> by [[Phoenix Typewriter]] on YouTube<br /> accessed on 2026-02-28T23:33:24

Duane Jensen replaces the felt in the hood of an Olympia SG1. Create a paper template, trace it out onto felt and cut it. Glue it in with contact cement. Some stores felt with self-adhesive on them as well.