A vintage wind-up alarm clock typically has a classic, retro design that was popular in the mid-20th century. It is powered by a mechanical spring mechanism that requires winding to keep the clock running. The winding key is usually located on the back of the clock.

The clock face is usually round with large, easy-to-read numbers and hands that indicate the time. The clock may have a second hand that moves in a smooth, sweeping motion around the clock face. The clock may also have a built-in alarm feature, with a separate alarm hand that can be set using a small knob on the back of the clock.

The clock may be housed in a metal or plastic case, often with a bell or bell-like ringing mechanism to sound the alarm. Some vintage wind-up alarm clocks may also have a snooze button that allows the user to delay the alarm for a few minutes.

Overall, vintage wind-up alarm clocks are known for their classic design, reliable mechanical movement, and nostalgic appeal.