The Circular Polarizer replacement packs of 5 or 10 allow the active GoPro Hero3 user to use and abuse their GoPro filters without the need to repurchase a full kit. This polarizer is a fantastic tool for GoPro shooters as it enhances sky, clouds, water, foliage and even snow. These filters will only work with the Formatt-Hitech GoPro Hero3 holder.