I'm sure you will be able to buy separately. I'm not sure either if I prefer it with top airflow, but fixing to find out soon as I have a top airflow coming. The thing I do like about the top airflow cap is it does have some knurling to grip the cap for refilling. I really like that, makes it easier to get a grip.I hope they will sell the top cap seperately then. I don't know if I want the top air or not. I suppose you can close it if you don't?