The AP RO dual time is a solid back 39mm case. Beautiful watch if you ask me. Available in SS with black, blue, or white dial on bracelet or PG with black or white dial on strap. Caliber 2329/2846 based on JLC movement has a 40+ hour Power reserve and 50m WR.
Seems like you are interested in this watch. I recommend visiting a nearby AP AD and trying on one. Let us know what you decide. Hope this helps.