Thereâ€™s no doubt that eye pro is always the way to go. The Valken Sierra Tactical Goggle features a TPU frame that offers the full seal protection needed in any force-on-force airsoft scenario. It also provides excellent resistance to both the cold and the heat. While an option for inserting prescription (Rx) lenses alleviates the need to wear glasses under the Sierra Tactical Goggle, the included dual pane lenses feature anti-fog coating and meet ANSI Z87.1 and CAN/CSA Z94.3-07 standards. These lenses, which also reach Military Combat Eye Protection (MCEP) ballistic requirements, also provide sufficient glare protection. In addition, a removable and wide adjustable elastic strap has a quick-release buckle.