I have had a hot ozi for yrs and like the photo above , have had this also for yrs.....
Even though I don't use the plastic stabiliser legs, I do reckon the 4kg bottle is a lot more stable than the smaller ones ( even though the smaller ones have the correct fitting already on them )
Mine has been getting a little "slow" of late, so after stuffing up the jet, I ordered another new one and the thing is going that well, I added another valve between the bbq and the above fitting to regulate the flow a bit better..