@MLE_online @zcopley @settinger I remember these from when I used them at work, back in the 1980s! I used to break the teeth on golfballs far too often, and a friend who'd worked for IBM told me they were only rated for typing speeds of up to 90 wpm... so I was typing faster than that. (She did too!)
@Knitronomicon @MLE_online @zcopley the teeth can break if you type too fast?? My goodness, I need to learn a lot more about selectrics!