@ PBG3 - 8 DAYS Antique Swiss Pocket Watch circa 1905 - Karachi - Jewelry - Watches - Nipa - swiss 1905
This looks very similar, but it is hinged. Now for Google-fu!
SCREW BACK & BEZEL CASES (POCKET WATCH):
This is probably the most common type of pocket watch cases around. The bezel (which is the glass side of the case) and the back is threaded in place and literally screws right off. These types of cases are identifiable by the fact that there are no hinges or raised lip areas. Under careful inspection there will be a very fine line of separation between the back of the case and the body of the case, and a very fine line of separation between the bezel (which is the ring that holds the crystal) and the body of the case. Look carefully for a small raised lip on either the back cover or bezel. This lip usually signifies where to pry with a case knife. If a lip is present on the back or the bezel, then it is a "snap-on" and not screwed on. If there is only one "fine line of separation", that between the bezel and the body of the case, then your case is a "Swing-out" case and the back will not screw off (see below). To unscrew the back of a Screw back & Bezel case, hold the watch dial down in the palm of your left hand, with the winding stem, more properly called the pendant, up against your left thumb. Much like the motion used when opening a jar of pickles, press the palm of your right hand down firmly on the back of the case and unscrew the back by turning it counter-clockwise.
From this site : OPENING A VINTAGE WRISTWATCH OR POCKET WATCH CASE