Saga makes high-quality flip diopter holders for just about any port. Constructed of anodized aluminum, they generally are threaded to accept 67mm diopters for most any brand.
At some point or another, underwater photographers are likely to experience a low-battery warning during a dive. Hopefully it occurs towards at the end of the dive, but for those of us unfortunate enough, the warning kicks in early and we end up carrying around a dead camera. Thankfully, there are plenty of ways to improve the camera’s battery life so that dreaded low-battery warning doesn’t ruin your dive.