|Proven in practice at 4°C water temperature.|
My HD Hero 3 Black Edition kept free from any fogging during a 47mins dive in 4°C waters. There was no fogging visible, neither within the housing nor on the front plate (front lens). Not even the slightest trace of fogging. Perfect results. Now if only under water conditions would have been better...
I can't but notice that for the premium I have to pay for GoPro's anti-fogging stips I get the two sets full of silica gel bags that can be seen in the photo, including shipping and handling. And then, these silica gel bags are much more effective and can be reused many more times. Please note that I hadn't any bag inside the housing during the dive, yet no fogging. So the bag effectively dried the housing as required during storing the housing between dives.
Note: Alternatively, since it's Valentine, you can buy your girlfriend a new bag and then some more during the year. This way, you will always get enough fresh silica gel bags as you need them.