Can anybody tell me if the oem omega deployment clasps are 18mm or 20mm?

Looking to purchase some leather and rubber straps for my Seamaster Professional 300m and wondering which deployment clasp I need.

I've heard people using both 20 and 21mm straps on the SMP. Which is correct?

 

A ref number of your SMP would help. They've been 21 (44mm chrono), 20 (most), and 18 (midsize).

Which deployant clasp you need will depend on the specific strap you're looking to put on the watch.

FYI, cheapest place for all of these new is your local boutique who are happy to help fit them to your watch.

 

212.30.41.20.01.003 is the ref number and I think I found the answer to my question. The bands should have a lug width of 20mm and the deployment claps is the 20/18mm.

 

Yes, your ref will have a 20mm lug width.

Deployant clasps will still vary by strap size, and deployant clasps are one measurement only.

Edit: also there are at least three different 18mm deployant clasps in steel: angled (newest), curved polished, and curved brushed.