Make sure to get the alternate inserts, as the stock ones may not reduce the airflow enough...depending on your tastes.
Personal observational trivia ...
I have several original full size Aspire Nautilus
tanks. That
tank is/was/still is a very popular MTL tank. Interestingly, the ring selectable air flow sizes on the Nautilus tank are .9mm, 1.1mm, 1.4mm and 1.8mm
Bear with me here. The VapeShell MTL inserts available add-ons at extra cost are 1mm, 1.2mm and 1.5mm.
The standard VapeShell inserts that come with the VapeShell are 2mm, 2.5mm, 3mm and 3.5mm. Without an airflow insert, the VapeShell will have 4mm airflow.
My point? ... If you've ever used a Nautilus tank, this information may give you some idea if you need the VapeShell MTL inserts or not. For instance, my preferred setting on the Nautilus is the largest airflow setting at 1.8mm. BUT ... the largest VapeShell MTL insert is only 1.5mm, which is slightly smaller than the largest Nautilus setting.
For my use, I found the largest VapeShell MTL insert @ 1.5mm to be slightly too restrictive. Therefore, I run the VapeShell with the SMALLEST STANDARD insert @ 2mm. It is only slightly larger than the largest airflow hole in the Nautilus which is 1.8mm. For my inhale technique which honestly is a combination of DL & MTL, I didn't actually need the VapeShell MTL inserts ... but still glad I have them