Katrin trains her legs with using her slave for testing different headscissors.
She orders him to a position, where she can clamp his head betweeen her legs, once between her well trained legs, she squeezes with all her power.
For him it must be like the head in a press... biological press!
When she changes the position she occasionalle steps on his hands and tramples them a little bit... she seems to love inflicting pain.
Then his head gets again in the sexy leg-press.