They are used when connecting to a belay point, fixing to a station, travelling on a railing, etc. It is not allowed to be in a position of self-assurance, in which a jerk with a large fall factor is possible. This may cause the station to collapse.
Two shoulders are convenient for travelling with the principle of continuity of insurance.
أخبرنا بما تحتاجه واحصل على عروض أسعار من موردين موثوقين