The EP-F Hydrophobia Eyepiece for Fuji X-H1, X-T3, X-T2, X-T1, GFX-50s from Think Tank Photo is a required watertight accessory for your Think Tank Photo Hydrophobia Rain Cover. It allows you to see through the camera's eyepiece once the rain cover is installed. The slide-on EP-F eyepiece is CNC-machined out of Delrin acetal resin and features high-density foam padding.