I was checking a spare DW-5600 that I have yesterday (a real bear to get the case back unscrewed). I finally managed to get the back off by soaking the watch in hot water & then putting ice directly on the case back. I was surprised when I opened the back & found that the 901 module had a CR 2016 battery in it! It seems very strange that a battery that small is used, so I checked my battery chart & that is what is specified. My other DW-5600 (691 module) has a CR 2320 battery in it; that looks correct as it fits in the battery compartment snug. Any body else seen this before? Is there a chance that the size of a CR 2016 has changed? I know the module is original to the watch & the hold down strap for the battery is stamped "2016" but there must be about an 1/8"/3.175 mm clearance all the way around the battery. It just doesn't seem the way to build a G-Shock. Anybody else seen this?