I purchased a Ragecams 5.4mm flat lens for my gopro, but didn't end up installing it as I moved away from the gopro system. This lens will remove the typical GoPro fish eye look, and give you some unreal photos and video. Read more about it here:
5.4mm Flat Lens No Fish Eye For Hero3+Black-White-Silver bokeh focus DJI Phantom | HD Wearable Video Custom Mods By RageCams
It's still brand new in the packaging (small jewelry box), and I've never used it. Paid $229.99 US$ new. Comes with daytime IR filter.
Make me an offer if this is something that interests you.
5.4mm Flat Lens No Fish Eye For Hero3+Black-White-Silver bokeh focus DJI Phantom | HD Wearable Video Custom Mods By RageCams
It's still brand new in the packaging (small jewelry box), and I've never used it. Paid $229.99 US$ new. Comes with daytime IR filter.
Make me an offer if this is something that interests you.