Petzl Knee Ascent SystemRound out your ZigZag SRT climbing gear with the Petzl Knee Ascent System. Designed to work with the ZigZag when used on a single rope, the Knee Ascent System helps you climb more efficiently with the attached Croll rope clamp and adjustable lower strap. Choose either a foot loop bottom strap or a clip style bottom strap. Weight: 1. 05lbs Accepted Rope Diameters: 8mm to 13mm Includes XS Petzl Toolbag for gear storage!! Upper strap, attached Croll rope