The slave on a high bench on his back, ready for to be a saddle for Yvette and Lena.
Yvette, in riding trousers (jodhpurs) shows the newcomer Lena how a face can be mounted like a horse, fullweight with the feet off the ground.
Then it's Lena's turn, she's a little bit careful and much lighter, but her jeans are tigh and hard, and yvette helps her with some extra weight.
And soon he gets sat on of both together, Yvette on his belly and Lena on the face, and reverse.