I have used these Sandmarc Aerial Filters before and now I ordered a second set because they are just brilliant! I also tried a different brand but they did not have the same build quality as these filters. I can highly recommend the Sandmarc Aerial Filters if you are still using a GoPro 3 or 4 on a DJI Phantom drone! On a sidenote: I had to contact the sandmarc support team because the shipment had somehow disappeared on its way to me and they are great too! Support was very fast, friendly and helpful. Thanks again, Sandmarc Team!
Quality, agility, efficience and fair price.