Los descendientes de espeleología se componen de una estructura de soporte que consta de dos bridas laterales y dos poleas internas de aluminio fijas, alrededor de las cuales corre el cable. El freno del descenso no es más que la fricción producida por la cuerda entre las dos poleas.
Petzl was founded by speleologists Fernand Petzl and Pierre Chevalier. They worked hard and improved their activity and sports climbing. In 1968 they began to produce gear, and they have been on the market since 1975. The company based in France has always been on the front line for innovation and developement: in 1991 Petzl produced the GRIGRI, the first ever belay device with assisted braking. In 2014 new seats were founded in Spain and Germany.
