Here we have a vintage new old stock, scissor link expansion band by Bretton.  It measures 5 1/3 inches at rest from end to end where it attaches to the spring bars and gives plenty of stretch.  The end pieces measure 16mm, and the band itself is just under 13mm wide.  This high polish gold-tone bracelet is in very good vintage condition, save for some minor shelf wear from storage over the years.