I’ve owned this one for about 15 years, but it was a lousy timekeeper, so I never wore it. It has a Landeron 48 movement in it. The case is a clamshell type, case held together by four stainless steel screws under the lugs. It has a “split stem”. Not my favourite option. Several years ago, I wondered what potential it had when serviced. So I serviced it. It’s not a chronometer, but it is within about 1 minute per week. I’m guessing that it may be circa 60 years old.