Make sure you get two. The propane locker on the 36 will hold both nicely, and when you run out of one you know its time to refill when you hook up the second. Also, if you buy the adapter and hose for your grill you can run the bbq off the spare bottle instead of hauling around 1 lb camping propane cannisters which are tough to store properly (only one fits in the propane locker on top of the two cylinders).