Black Diamond ATC-Guide Belay Device Multiple friction modes for belay and rappel. Machined windows through device for weight savings. Auto-block release hole accepts small carabiners. Durable cable holds its shape and resists getting caught up between ropes. Guide mode works with one or two climbers. Ascending and descending. Dependable and smooth operation in all conditions, handling ropes from 7.7 to 11 mm. Weight: 88 g (3.1 oz.).