I've been told the "S" stands for "small".
Well yeah, if it's only got 2-4 drops in it you're fine. But when someone's looking for a "leak-proof" device, the IGO-L isn't really it. I don't overfill and it still leaks.
I bored out the hole slightly -- I think it's a #58 drill bit I used. A tiny bit bigger than stock. I did it without a drill, just spinning the bit in the hole if that gives you an idea of how small it is.
My point is that mine holds 20-30 drops without being "overfilled" or gurgly -- and it will leak. If you are happy with 4 or 5 drops and vape it all 'til it's dry, you'll be fine.