The Timex caliber M72 is the oldest 21 jewel movement, made by Timex. It was introduced in 1961.
In contrast to “normal” 21 jewel movements, on this caliber, only the axes of the gears were pivoted in jewels, the balance was still pivoted in brass pivots.
This hybrid of a cheap non-jeweled and a “good” fully jewels watch was better than a non-jeweled watch, but far below a good swiss fully jeweled movement.
As you can see, most bearings were covered by deck jewels, which were bordered in a kind of chaton. These deck jewels are, maybe except the anchor wheels' deck jewel, not really needed, but they helped to reach the high number of 21 jewels. Maybe, Timex hoped, that their “21 jewels” watches were seen superior to generic (but nevertheless technically advanced) “17 jewels” watches.
Since Timex watches were always regarded as rather cheap watches, the expensive “Timex 21” models did not sell that good and in the early 1970ies, they disappeared from the scene. A certain collectors value cannot be denied, though.
|Number of jewels:||21|
Nickel anular balance|
|Balance bearing / direction hairspring:||Bridge|
|Adjust mechanism:||Hairspring key|