The sleek, ergonomically designed Vortex® Diamondback® HD Binoculars are fast to get on target, and comfortable to hold for extended periods of glassing. An HD optical system improves resolution, and multiple anti-reflective coatings on all air-to-glass surfaces and multi-layer prism coatings enhance light transmission. A lightweight magnesium chassis provides extreme durability, and rubber armor exterior provides a secure hold and helps to absorb shock. Vortex binoculars are argon gas-purged and O-ring sealed for. waterproof. performance, and to prevent internal fogging over a wide range of temperatures. A center focus wheel adjusts the focus of both binocular barrels at the same time, and twist and lock eyecups provide comfort with or without eyeglasses. Includes Glasspak™ bino harness, tethered objective lens covers, rainguard eyepiece cover, neck strap, lens cloth, and product manuals. 15x56 model also includes a hex wrench and tripod adapter. Mfrs. lifetime warranty. HD optical system. Lightweight magnesium chassis. Multiple anti-reflective lens coatings. Multi-layer prism coatings. Rubber armor exterior. Waterproof. /fogproof. Includes Glasspak binocular harness