SeaLife ReefMaster RM-4K Spare Battery

I've been burned by cheap knock-off batteries dying mid-dive, so getting this genuine spare that fits the camera perfectly was a relief. It's held its charge for weeks between trips, which is exactly what I need as a backup.

I swapped this in between dives and it held a full charge for over an hour of 4K recording, which was a relief. The battery clicks in securely and didn't budge even in rough currents.

Finally got to use this on a liveaboard trip and it lasted through three full dives without any issues. The battery indicator on the camera showed a steady charge the whole time. Glad I had a backup for my afternoon dives.