Abstract: A jack (1) has a jack body (2) with a peripheral wall (3) which forms a jack chamber (4). Two pistons (5a, 5b) attached to piston rods (6) are movably mounted in the jack chamber. The jack (1) has an automatic locking section (MV) to lock the two pistons (5a, 5b) and their respective rods (6) in at least one of two extreme positions. The locking is done automatically during the movement of the pistons (5a, 5b) by locking balls (11a, 11b) which move in locking grooves (10a, 10b) in the piston (6). There is also a manual unlocking device (MDV) connected to the pistons (5a, 5b) through unlocking rods (21). The manual unlocking device (MDV) is attached to two unlocking collars (7a, 7b) which rotate to unlock the piston (5a, 5b) and piston rod (6). The rotation, in turn, moves adjustment screws (23) to displace the unlocking rods (21) along their axes.

Abstract: A snap-hook for use with ropes or the like, primarily for rock-climbing, made up of a body or hook in the shape of a "C" of which the straight rear central portion is extended by two curved arms, one upper, the other lower, of which the free ends are joined, on closing the snap-hook, by a pivoting finger moving on one of these two ends, said snap-hook comprising an internal periphery having an essentially semi-circular cross-section and an external periphery which is formed, on at least the whole length of the upper and lower arms, of a rib of uniform section, designed to increase the rigidity of the said upper and lower arms, without increasing, and even lightening, the weight of the snap-hook.