I have also received mine from Sead. I'm very satisfied with the watch, but can't figure a way out to adjust/shorten the jubilee bracelet. Did anyone of you manage that? Which tool size did you use. The screws seem to be smaller than the normal bracelet screws. :-(
The only way to adjust length on a hidden clasp jubilee bracelet is to add or remove a link, a 6mm change. Sad but true. There is such a thing as a 1 1/4 jubilee link, but it's a gen part. I've not seen it aftermarket.
Glidelock step adjustment 2mm
Standard clasp pin adjustment 3mm
Easylink adjustment 5mm
Half oyster link adjustment 6mm
Full jubilee link adjustment 6mm
1 1/4 jubilee link adjustment 7.5mm
Full oyster link adjustment 12mm
The GMF Batman with jubilee does not have a hidden clasp. So there should be a springbar inside the clasp with 3 positions, 3mm apart. Loosen the springbar just like the one attaching the bracelet to the case. Often you can just loosen one side and push it to the next detent, then follow with the other side. Sometimes it will come out altogether. Just put it back where it will give you the change you need. You may have to use a combination of link removal and clasp springbar position change.