A tight draw means the air intake is small. You have to pull harder, like sipping a thick milkshake. This is the classic mouth-to-lung (MTL) style, where you draw vapor into your mouth first, then inhale it into your lungs. It feels a lot like smoking a cigarette, which is why many ex-smokers prefer it.

An open draw, on the other hand, lets in a lot of air. The pull is easy and airy, like breathing in fresh air. This suits a direct-to-lung (DTL) style, where you inhale the vapor straight to your lungs. It's the go-to for cloud chasers because it produces big, voluminous clouds.

Most adjustable devices, including models like the VERTEX-VISTA and LINQ-PRO, let you slide between these two extremes. Some even have a range of clicks or stops so you can fine-tune the exact amount of air.