* Does the bowl vibrate?
Vibration naturally causes heavier material to settle into the grooves
* Are the riffles undercut?
is great for trapping gold and allowing lighter materials to wash away
* How big or far do the lead in riffles reach out of the bottom of the bowl?
riffles sometimes don't have a chance to grab gold before it washes out
* Is the bowl one, solid piece?
or tabs disrupt grooves and gold recovery
* How sturdy is the bowl?
Extreme temperature and UV light can warp or deteoriate a bowl
* Is the center tube stainless steel?
allows the bowl to be used for amalgamation of concentrates