From time to time we will revisit some much older patents. They show us some ideas that either never caught on, or did but have since been improved upon or gone out of style.
This Benrus patent was issued in 1952 and expired in 1969.
This patent disclosed a simpler way to adjust watch bracelets. The bracelet features a traditional tri-fold clasp, but also allows quick adjustment to make the bracelet tighter or looser. An internal spring bar and several notches allow the user to easily adjust the fit of the bracelet while it is still on their arm, all invisible to the user.
The patent suggests that on hot days you may want a little more room in the bracelet, or to quickly push it up your arm while washing your hands.
It's a clever idea, though I don't know that it was ever mass produced. And certainly the spring bar would loose resilience over time and the bracelet would begin to slip, which is a major downside.
Meanwhile, we have seen some quick fine adjust mechanisms on bracelet clasps lately, but none that I'm aware of that let you adjust the fit while it's on your arm.