Ava Krass domme face sitting – I train a slave, sitting on his face with a stopwatch in my hand

I train the slave to hold his breath for a while, restricting his breathing, with a stopwatch in my hand, sitting on his face, longer and longer, I want to understand what is the maximum time he can withstand under my ass without breathing. He’s trying to breathe, but I’m sitting on his stupid face with all my weight.