A balloon (10) extending generally axially from an opening (14) at a first end. The balloon comprises an elastomeric film (11) having a first thickness and a plurality of intersecting ribs (12) of a second, greater thickness formed on the film The ribs are adapted so as to be angled with respect to the axis (13) of the balloon and any axis perpendicular thereto. Such a balloon has increased tear resistance, and can be manufactured with conventional dipping techniques without compromising the integrity of the film. The ribs may comprise a plurality of helices. There is also a former for making such a balloon and a method of using such a former to make such a balloon.
