Exclusive cuved cam interface impresses rope into a special frame cavity to grip rope securely and without damage. RESCUESCENDER and MICROSCENDER are designed to slip on rope, rather than cut sheath if overloaded - 3 kN for 9mm ropes and 4 kN for larger diameters. . MICROSCENDER is a handy "pocket sized" solution for personal and emergency use. Popular with big wall climbers as a 'third hand" (backup to handled ascenders) and also mountain rescue teams. Clamps securely on wet, icey or muddy ropes in response to cable spring tension on cam and also load. Fits ropes up to 1/2" (12.7 mm). Available in all black for $2 more.