Lightly used, No. 647's are 20mm and work well with many Speedmaster and Seamaster bracelets. $80/pair. $5 shipping for the CONUS. Shipping elsewhere at my cost. Payment via Wise, Revolut, Venmo, Zelle or PayPal F&F. Returns accepted for a full refund, less shipping, no questions asked, if initated within 7 days of receipt and as long as I receive them back in the same condition as shipped (i.e., no alterations). Buyer pays for return shipping. Please PM me if you would like photos. Thanks for looking and thanks to OF for the space.