Help

 Just received a mans watch with another I bought at auction. High grade probably RGF case in very nice condition. Stainless back no writing on outside. Case back says " id" watch case co. Mvmnt is 21j, 4 adjustment  Exello watch co. Swiss  no serial #? case back has 566276 inside. Sorry but i cant find any info. After cleaning and oiling watch runs perfectly. Seems to be approx 1940s style. Thanks