The waterproof lens uses mirrors to capture two left/right images, so there's no stitching required. Using it is simple for those who may not be familiar with 3D filmmaking; it pops right onto a standard GoPro housing. It doesn't require any software and is immediately viewable through a VR headset, which means that there's no editing required.
This video shows you what using one looks like:
And here are a few sample videos to show you what it records:
The Vitrima 3D lens costs only $50, which is a pretty good deal if you're interested in toying with the idea of shooting your GoPro stuff in 3D but don't want to break the bank to do it. Vitrima hasn't launched quite yet, but you can sign up to get notified when they become available.