Cecily sighed. "It's almost no fun when you're so smart, you know. But yes, a rather brilliant invention of my own, if you must know. Like one-way glass only portable, invisible, and more like a box than a wall. Awfully convenient, let me tell you. It doesn't hurt them, as they can very well attest. They can hear us, but we can't hear them. A mercy, as the yelling was quite sonorous." She tapped a thin finger on the invisible barrier over Blaise's chest.