What do you use a 1/8 x 1/8 inch square notch trowel for?

What tile do you install with a 1/8 x 1/8 inch square notch trowel? What size is the Kerdi Trowel?
See trowel on Amazon. Affiliate link below.
1/8 x 1/8 square notch trowel: amzn.to/3rQpG3q
Kerdi Trowel: amzn.to/3tXfJD3
As an Amazon Associate, I may earn a commission from qualifying purchases

[@gurpmcullen6259]

You're great, man.

[@chase7359]

Thank you