Sweet pix! Glad this baby got bumped-up.
One thing I especially like about the scene is, it appears it's a slave-tickling-slave scenario. There's something cool about the idea of someone being forced to tickle another, especially in such a difficult predicament. Unlike with a dom/sub scene, the tickler in these pics might not know whether she herself may wind up in the same situation next!
On the mask: I've been in a similar hood. Typiclaly, they have noseholes for breathing. Not easily seen unless the camera-angle is from below the person's face.