Katrin meets her slave on the high bench, she binds his wrists with some leather-belts... now he's ready for to be her seat.
She comes over his face, shakes her ass over him, teasing him with this view, before she descends and he has to receive her whole weight on his face.
Her hotpants are tight, the bench is so high, that she could lift her feet off the ground, means his face gets seriously crushed under her ass and all her weight.
If he struggles to much, because the lack of air and the immens pressure on his face, she may (or not!) lift her ass, shaking and teasing him for some moments, only for burriy his face again and continue with her heavy-ass-facecrushing-lesson!
Struggling or resisting?... not under Katrins 150+ lbs ass!