13.5MM

I found this item because the broken guts of my old clock has the 12888 model number stamped on the back of the mechanism. I wasn't sure this would work since my clock was large and had long hands, but it swapped out flawlessly. I didn't use any of the included hour/minute/second hands and was a little worried since my existing minute hand was slotted (rather than a round hole), but the slot was the same bore as the spindle in this and it worked like a charm. Add on the cap from this replacement kit (in lieu of the second hand) and I've essentially got a brand new clock for under ten bucks.

Keeps good time and easy to install

Used this to replace the clock mechanism on a clock from the 80s. Works perfect, accurate time and an easy install.

Perfect replacement

dropped right in place, these clock cores are a perfect fit.

This item works as intended.

I used it to replace the motor in a 40-year-old wall clock. The old motor still runs (!!) but the gears are getting worn, so it uses up a battery (C cell) in just 2-3 months. The new motor is extremely quiet, it was easy to install and set up, and I anticipate longer battery life...but I'll update this review if needed.

Worked fine with slight modification of length of hands

My beloved clock suddenly died and days of searching later I could not find another one that I liked so I decided to try to replace the mechanism. Searched Amazon and decided I liked this one. A few days later and it arrived. Removed 4 screws and one nut, dropped in the new motor. Replaced the nut, pushed on the hands replaced replaced the screws and after inserting a new battery replaced the clock on the wall. Bingo clock running better than ever..

It is a fluid movement mechanism rather than a tik tok tik tok style of mechanism. Therefore it makes no noise. In the past month it hasn't lost any time that I have noticed.

Good device. Keeps good time. It replaced a unit in an imported clock that didn't work properly.