Belgium Folding Trigger 6 shot Revolver, Serial number 13!

Listed for sale is a Belgium Folding Trigger Revolver. I am not familiar with these types of revolvers so I do not know the caliber, but based on my limited research, these were manufactured prior to 1889 qualifying it as an antique. It features a 2 ¾” barrel and 6 shot cylinder. There are numerous stampings on the revolver and I tried to capture most of them in the photos. For lack of knowledge, I am calling this revolver serial number 13 as that is the number found most often on the revolver. This is found on the back of cylinder, barrel, left frame, ejection rod, one grip panel, and trigger. Number 92 is also shown on the right of the frame and the front of the cylinder. The revolver functions normally in both single and double action with a little wiggle at lock up.
The folding trigger works as designed as does the ejection rob and hinged loading gate. The wood grips are in very good condition and fit the revolver nicely. The blued finish is worn.
Overall a very interesting piece.