Review (5/5): Nice! I got the XL size and it is awesome for carrying my diffuser to work!
Fits my Plant Therapy NovaFuse USB Diffuser (6.31"x4.72" 70ml reservoir) beautifully. See the photos.
The zipper is nice. It has double pulls and is a nice weight- it isn't a wimpy zipper. :)
The strap on the top seems put in well.
My diffuser is a USB Diffuser. It only has the one cord without a plug so I can put a baggie of smaller 1 and 2ml bottles into the special plug sized pocket with the cord. :)
Bottles- it will hold the 30ml bottles, just not in every place. You have to do a 30ml bottle with either 10ml or 15ml on either side. I currently have four 30ml bottles in mine. You may be able to get 1 or 2 more 30ml bottles in it if you try and don't mind not having room for other bottles.
I gave it 4 stars for sturdiness as it is a soft side case. I would love for it to have a bit more "shape" -There is no firm form to it, and not a lot to protect the items inside from casual bumping damage. It is simply an "I am going to carry this diffuser to work" type bag.
Do not put your stuff in this bag then toss it in a large suitcase thinking it will be protected while the guys at the airport throw your suitcase around. If the bag gets turned upside down then your stuff inside is going to move around. No straps to keep things in place. It wasn't designed, not intended for such use.