The ATC Guide Belay Device is already worthy of any climber's arsenal, but Black Diamond made it even better for alpinists and crag-stars alike. It still transcends the tube/auto-blocking category, allowing for a standard belay as well as belaying one or two climbers off anchors. Black Diamond upgraded it with machined windows for a lighter weight, and the larger auto-block release accepts smaller carabiners for a smoother and more dependable operation.