A Demist Shield is a protective accessory that snaps onto the ocular lens of PVS-14 pattern optics. It prevents condensation from forming on the lens during temperature changes and protects against scratches during transport. The ocular lens must have an eyecup retaining ring installed, which can be found here. This shield is not recommended for use on objective (front) lenses. This product will not protect against BBs or sim rounds, for a more comprehensive protection device, see here.