It’s just the right size so that air flow is not really restricted at all. I wouldn’t put any rings around it – they’d just draw DMT toward the glass. No need to keep it centered – it’s sized just right so that no matter where it is, the opening at the bottom of the GVG chamber is always fully covered.

Since it’s ceramic, the best way to clean it is to blast it with a torch lighter until it begins to glow. If handled gently, one disc could last forever.

One thing I didn’t mention – I don’t put a screen in the GVG when using these. The screen would raise it above the base of the bowl too much and allow air to flow around it rather than through it.