GoPro accessory maker Polar Pro got its start in 2011 making a simple polarizer filter for Hero cams.
It didn't stop there, though, and the company now has the Venture3+ combo pack that includes polarizer and neutral density (ND) filters and a 3.8x macro lens.
The most important filter in the pack for most people will be that original fixed horizontal polarizer. It helps tame glare off of water or snow or really any reflective surface. It will also make your blue skies pop a bit more.
The ND filter basically slows down the shutter speed of the Hero3+. By doing this you can create motion blur in clips where you're traveling at high speeds. An ND filter will also help cut down on wobble from rolling shutter and with blown-out highlights in really bright scenes.
The macro lens is more specialized than the filters. You're probably not going to use this when you're out in surf or barreling down a ski slope. It has a 3.8x magnification and allows you to shoot as close as 2 inches (5.1 cm) from a subject, something the Hero 3+ can't do on its own.
There is some distortion at the edges and in the corners if you use the camera's ultrawide field-of-view settings, but it's sort of a nice effect. The Polar Pro site has some sample videos up if you want to see just what these can do for your videos.
The filters and lens are glass, but the frames are all made from ABS plastic, so they're lightweight but can still take some abuse. Each lens gets its own microfiber pouch for storage and cleaning.
What's nice about the design is that they just push on around the lens of the GoPro Hero 3+ housing (Polar Pro has other versions that can be used without the housing). It's a snug fit so they shouldn't pop off if you wreck and it means you don't have to do anything to the housing that may compromise the waterproofing. And when you're done, you can just pull them off.
Again, the plastic frames should hold up OK, but it does make them look and feel kind of cheap, especially compared to the all-metal mounts, lenses, and filters from Fotodiox Pro's GoTough line.