Filter Adapter for Go Pro 5 58mm [GF-FAR58] - $7.95 : GTX Products Group
Adapter Rings
2X 58mm Filter Mount Adapter Holder for GoPro Hero 5 GoPro Camera Go Pro | eBay
58mm 16x Close-up Magnifier Lens Filter For GoPro Hero 3+ 4 5 6 7 black & case | eBay
Amazon.com : Dive Filter for for Gopro5 Action Camera, 58mm Optical Glass Underwater Photography Filter Red Diving Filter with 16X Macro Lens, for Various Underwater Video and Photography : Electronics