The Frog ascending system utilizes two ascenders and progress up the rope is made by shifting weight from one ascender to the other and advancing the unweighted ascender. The climbing motion cycles between sitting in the seat harness and standing in the foot-loop. This sit-stand motion looks a little like the kicking legs of a frog while swimming. When combined with the fact that the ascending system was developed by the French, the name becomes apparent. The Frog system uses a caving style seat harness with two attachment loops that are joined together with a demi-rond maillon (half-round quick link). A specially designed chest ascender attaches directly to this central maillon and is held upright with a simple chest harness. A pair of cowstails are used for various rope maneuvers, and the longer of the two tails is generally used as a tether to attach to a foot-loop ascender that rides above the chest ascender. A foot-loop attached to this upper ascender completes the system. There are a few variations, and the most common is to add a foot ascender to help with climbing efficiency.