Abstract: Forceps have two branches movable opposite one another against a spring force and with a lock that fixes the distance between the branches. The lock engages as the two branches approach one another and is released by closing the branches further. This locking mechanism includes a locking arm mounted between the branches with a free end that rides between a sliding surface located on the inside wall of one of the branches and a guide member. The free end carries a locking element that engages a locking step formed on the sliding surface. The guide urges the locking element against the locking step and then, with a further closing movement of the branches, directs the locking arm free end to its initial, fully opened position. The guide has an enlarged opening that allows the free end to fall back onto the sliding surface.