The idea behind the opaque bottom bangers is that the micro air bubbles in the bottom will create more surface area to heat up, thus keeping your banger heated for longer. This is what the internet says, but we find it to be bullshit.
Heat is held by mass with the small air bubbles the mass is actually reduced by 20-40%. We feel these are a gimmick and we recommend the thickest banger you can if you want heat retention.
You can learn more here about bangers in our blog.