Arrived some times ago,vintage diver watch,ERSTER, 20 Atmos ,numbered case,i think Felsa calibre,big size,around 38 mm,bidirectional bezel,all stainless steel.I think is from 60's.I don't know too many about Erster watchs,i find just some poor information about Erster -Squale.I will be grateful for more information about him.