No purpose, just two styles. And originally they were 19mm at the lug and short there too for a Speedmaster.
Astronauts nerded out so we nerd out, Comfortable to wear, too.
Don't over analyze this.😁
Now where'd I put my pocket-protector?
If you are putting on a Speedmaster pro do you use the bracelet springbars? Or the shorter ones for the NATO? Any reason to use one over the other?
It really looks good on the straight lugs.
I find them difficult to use. The clasp seems hard to attach and even harder for me to release, I’ll see if I can get used to it with time. OTOH the bracelets are very comfortable.
Try pressing the bottom of the clasp up with your thumb with a little pressure while using your index finger on the clasp button. It helps alot when putting on and taking off .
Sorry to chime in here, but don’t forget about the instructional videos on the site. The clasp should be very easy to remove with only small pressure downward on the button (as per the instructional video).