The ATC Alpine Guide by Black Diamond is the most versatile belay/rappel device, with machined windows through the body to save weight. 

Features:
• Multiple friction modes for belay and rappel
• Machined windows through device for weight savings
• Auto-block release hole accepts small carabiners
• Extra-large anchor hole to allow for ropes
• 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 6,9 bis 9 mm