ABC Ascender CE Certified Rope Clamp for 8~13MM Rope Our patented ascenders are strong, work on ropes from 8mm to 13mm and come with a patented lever that, when suppressed, allows for safe and easy down climbing without removing the ascender from the rope. Complete with a comfortable rubber grip that stays that way even in harsh, wet conditions. The rope cam is designed to hold even on dirty, muddy or icy ropes.