5 gallon propane tanks. I Have a couple empty and/ or partially full and also have a couple full tanks. $30 for an empty tank $55 for a full tank. Empty tanks can be swapped out at Home Depot or similar store for a full tank for about $20 if they are open. but if it’s after hours, I have full tanks too. They can also be filled or topped off at any place that fills propane tanks for usually less than a tank swap. Reason for selling, We sold a property and have excess tanks we don’t really need.