4 ms·The Unicomp Model M continuations are still good, as well.by timw4mail 5y agoThe Unicomp Model M continuations are still good, as well.flatiron 5y agoim typing on one right now. i have to figure out how to clean the keys, some have some coffee stains :)ch_123 5y agoThe plastic is pretty durable (PBT) - you can scrub with them with dish soap. Isopropyl Alcohol should be fine too if you want something stronger.