Nang cylinders are small, metallic canisters crammed with nitrous oxide

https://bbarlock.com/index.php/A_Day_in_the_Life_of_a_24-Hour_Nang_Cylinder_Delivery_Service_in_Melbourne

Nang cylinders are small, metallic canisters crammed with nitrous oxide, normally used in culinary purposes to create whipped cream and different foams.