could have been a viable product [SEP] bad design the pictures in the posting show or imply that the glass vial threads screw into the top inhaler brass colored section it does not it just holds by supposedly a friction tight fit so not only is it a loose physical fit it also allows your oil or scent to leak out and or dry up prematurely this is the only problem i have with these inhalers and it is a major one they got sent back on the search for some quality ones that actually properly seal in the vapors