Setting the high-water mark for belay devices, the Petzl GRIGRI has only gotten better with age. Climbers can expect a greater measure of security with its cam-assisted blocking. Lightweight, compact, and durable construction make it a welcome companion for both indoor and outdoor climbing. And its dynamic single rope compatibility ranges from 8.5 to 11 mm (optimized for those 8.9 to 10.5 mms) while lending smooth and progressive control with the ergonomic handle.