The Echo Full Size binocular is built around BaK-4 prism glass with our famous Emerald Fire full multi-coating. We gave our Echo line our new twist-up eye relief system for eyeglass compatibility and more comfortable viewing. The Echo is value. Waterproof, fogproof, and nitrogen filled this optic is a great buy. The frame is a polymer material covered with our feel good ergonomic body armor. Compatible for tripod or monopod and is honored by a 5 year warranty.