PolarPro "Frame" Glass Neutral Density Filter for GoPro P1006
GO PRO HERO4 Accessories,ND filter / Neutral density / Lens Filter for Gopro Hero 4 / 3+ / 3 action camera (with tracking code)|filters for gopro|lens filterneutral density - AliExpress
GoPro red filter - When and how to use it for snorkeling and diving
5 Filter Lens Underwater Package For GoPro Hero 3 & Hero 4 Sporting Goods Other SCUBA & Snorkeling romeinformation.it
Nflightcam Propeller Filter for GoPro Hero3+ and Hero4 – Nflightcam.com
Diving Lens Filter Kit Compatible with GoPro Hero 4 Hero+ Hero and 3+ fits Standard Waterproof Housing Enhances Colors for Underwater Video and Photography Includes 5 Filters - Newegg.com
Luxebell New Design Underwater Dive Red Filter Lens with LUXEBELL Microfiber Cleaning Cloth for Gopro Hero4,hero3+ Camera - Luxebell Official Webiste