This has grooves carved into the foot – this helps to release liquid in your dishrack/dishwasher etc.
It was grooved, due to a need for sanding the bottom from glaze drips.This does not affect the body of the mug, but I would want you to see the bottom – please check the pics.
(The mug #161 is very similar to the mug #40 shown here) however the bottom has signs of grinding/sanding and there are several notches carved out of the bottom foot as shown in the video sent to you (Harvey) via email, Jan 13/22. The mug will be the same one as you saw in that video. Bottom of mug is as shown in the image here 161B.)
all prices are in US funds