Here's what other sites are saying:
The Petzl Nitro Shock-Absorbing Sling reduces the impact force exerted on protection in the event of a severe fall. Improves security from dubious gear, placements, and dislodged pieces.. . . Energy-absorbing device activates at 2.5 kN, and holds to breaking strength of 22 kN. Nylon material; Velcro tab prevents branches from hanging down and catching on other gear. Size 3 Nitro reduces impact up to 50% for maximum energy reduction. Size 3 dimensions: 16 cm. CE/UIAA certification.
The Petzl Nitro 3 shock-absorbing sling is used as an energy-absorbing device for climbing, rescue and caving applications. Absorbs shock to prevent small pieces, dubious placements or anchors from dislodging during a fall; great for ice, mixed ground and traditional climbs. Helps improve security of anchors such as ice screws, small nuts and pitons. Webbing is folded and stitched in a way that the stitches will pull out under force and reduce the shock load on the anchor or protection piece. Outer hook-and-loop strap holds the folded webbing in place until shock loaded. Includes a Petzl String to ensure proper alignment of carabiner and extra abrasion protection. Activation force: 2.5 kN; Breaking strength: 22 kN.