Hi guys. You probably know that Eneloop Pro batteries are a bit more thick that standard AA batteries. Actually the difference is small and this never was an issue for me with older Garmin navigators. But after installing Eneloop Pro in my GPSMAP 66 I noticed that battery cover rises above the case a little bit higher than with standard batteries. I was concerned if this affects water sealing, so I made an experiment and "washed" GPSMAP 66 under running water. When I opened battery case there was some water inside Then I wiped the device and repeated the experiment with classic white Eneloops, this time no water got inside. I'm still not 100% sure to blame Garmin (may be it's just my device has a broken water sealing or it's case is not adjusted well), but anyway it's a thing to consider especially if your device usage includes water activities. Cheers!