This Formatt-Hitech Clear Protector Filter Kit contains 5 replacement filters for use with the Formatt-Hitech GoPro Hero 3 filter holder. These optically clear filters serve as a convenient means to protect the front element of your GoPro Hero 3 camera housing as well as other filters in use. Each filter measures 33 x 36mm, is 1mm-thick, and is constructed from CR-39 resin.