Will this fit a Movado 800 series watch?

It should, but you'd have to measure the distance between the lug ends to know for sure. Most are between 18-24mm, measured by a simple ruler.

I have a baume & mercier clifton 50mm watch. what is my band size?

I have checked your watch model, but sorry to tell you that we can’t find which size will be fit for the baume & mercier clifton 50mm watch. To confirm the most suitable size, you can : 1. Check the underside of your watch band to find whether the width is marked; 2. Check your watch manufacturer’s specs to find the proper size; 3. Use the metric ruler to measure the space between your watch’s lugs; If you have any other problem, please feel free to inquire us, we are always happy to serve you here.

Are the ends of this watch band slightly more than 24mm? My watch lug is slightly more than 24mm and I want the watch band to fit without any spaces

I'm getting a measurement of 23.95mm in width on the band

So to remove a pin you have to push on the opposite side that looks kinda split? Why no arrows to show pin direction?

I had to look at my Binlun bracelet to check, and you're right, there are no arrows. I don't know why they don't have them. In my case, I noticed an Amazon customer review of the bracelet I'd just ordered that explained how to remove the pins, and had no problem removing links from my bracelet to make it fit.