The GG&G EOTech Lens Covers fit between the EOTech hood and the body of the EOTech housing. They are spring operated so that once pressure is applied to release them from the closed position" they spring open. The rear cover lays across the top" so as not to interfere with the field of view. The front cover opens and serves as a sun shield. However" if heavy brush etc. is encountered" the front lens will fold back so that it is not damaged. Because of the contours of the EOTech housing" these rifle scope lens covers are not 100% waterproof" but they do prevent most dust" debris" rain and snow from accumulating on the lenses.