Machines for making aerated and non-aerated beverages, and parts therefor; non-electronic, non-refrigerated machines for dispensing beverages, and parts therefor; post-mix soda guns, namely, beverage dispensing machines, not automated and not heated or cooled, and parts therefor; post-mix soda guns, namely, machines for making beverages from syrups and water, and parts therefor; post-mix bar guns, namely, handheld beverage dispensing machines, not automated and not heated or cooled, and parts therefor