Depending on how intensively they are used and the sort of terrain, ambient humidity, etc., to avoid oxidation, Obut Lisse boules stainless steel Leisure boules require a little care and attention after each game and at least once a month if they are not used. Do not leave your boules in the boot of your car: it is exposed to sudden changes in temperature that cause condensation. In the long term, this high humidity will be detrimental to your boules by creating conditions that lead to rusting.