Original von elmar2001

Die gibt es nur nicht. Endweder Plexi und Stahlboden oder Saphir und Glasboden

"Two versions of the Speedmaster do have a display back , one (now discontinued) have an hesalite crystal (3572.50) the other the sapphire crystal (3573.50) both share the "luxury" finish version of the 861/1861 movement the 863/1863"

(c) http://www.speedmaster-mission.net/