White knight
You can choose whether you would like a white or a silver metal base for your face drinks bottle. Because we don't use white ink this can affect the way that the finished design looks. Basically, the white areas are left unprinted, and so show up as silver on the silver coloured bottle. This gives your thermal face bottle a look of authenticity and charm, however light colours will show up better on the white version.
The other slight difference between the two is that the white is a little stumpier; slightly shorter in height but a less graduated slimming of the bottleneck. Both face drinks bottles hold the same amount of liquid, however.
Steady on
Your face drinks bottle has a ridged base, similar to that of a fizzy drinks bottle that you can grab from the corner shop or supermarket. These aren't accidental, they actually provide additional sturdiness to the bottle. It gives the bottle more structural integrity, it stops condensation from collecting at the base and making the bottom slippy.
TLDR: there are grooves at the bottom to make the bottle more sturdy, because science.