5161 is the movement or module number when looking up English instructions. I have several of these Casio WVA series watches and this is a nice addition. I was drawn to the comfortable olive canvas looking strap that I find most appealing. Although I'll probably add a 20mm deployment clasp, this strap may be difficult to clean after inadvertent exposure to dirt, grease or grime. The dial's outer seconds/minute ring is dark grey. The face color is a dark olive brown and gives good contrast to the easy to read numbers around the dial. I am surprised they have a good glow at night in addition to the hands. An unexpected plus. Easy to read from bed at 5:00 a.m. without having to push the light button. The crystal is flat, acrylic and not slightly domed like the other WVA's. My watch came direct from Japan with a last time sync of Nov. 23 @ 12:19pm. Now mid May, it was just a little off but synced quickly to Colorado. The home positions of the second and minute hand were off as well but easily adjusted by following pages E-63 - E-66 in the manual. Language for the days of the week was of course Japanese but a couple button presses and it's in English. Overall I really like it and look forward to wearing it on my next outdoor adventure.

The watch has a solid resin case with thin stainless steel shell top and bottom. This gives the watch a light weight solid construction. The exposed resin areas around the perimeter have a bonded silver coating which can be scraped off with a sharp knife. It is highly doubtful that any of this could flake off over time in normal use. This is an improvement over other WVA's which have the edges of their light grey molded resin case uncoated and exposed.